Installation for utilizing surplus heat from a power transformer

Abstract

The invention relates to an installation for utilizing surplus heat from a power transformer. A first pipe system (7) is connected to the cooling device of the transformer for circulation of a first, heat carrying fluid between the transformer and a heat pump (5) with the purpose of enabling emission of heat to an evaporator (10) included in the heat pump, which evaporator via a second pipe system (11) containing a second fluid communicates with a compressor (12), a condenser (13) and an expansion valve (14), a third pipe system (15) having a third, heat carrying fluid for transfer of heat to one or more consumption units (16) being connected to the condenser. A fourth pipe system (19) is directly or indirectly connected to the first pipe system (7), which is partly brought down in a combined heat accumulator and emitter (20) in rock, ground and/or water, a multi-port valve (23) acting between the first and fourth pipe systems (7, 19) for enabling leading of surplus heat from the transformer via the first pipe system to either the evaporator (10) of the heat pump or said heat accumulator or emitter (20).

Description

BACKGROUND OF THE INVENTION

[0001] In the windings of power transformers, heat is generated which has to be evacuated from the transformer and the immediate vicinity thereof. In small transformers, this is usually carried out by air-cooling via cooling flanges, while larger transformers are cooled by means of oil, e.g. by circulating oil, such as mineral oil, through the windings of the transformer and ducts in the core thereof, or alternatively by the fact that the core and the windings are immersed in an oil bath in an outer container. Irrespective of which type of cooling device being used, the heat evacuation constitutes a waste of energy, as well as a practical and economic problem so far that inefficient cooling and high temperatures results in premature deterioration of the transformer and the equipment in connection thereto. A particular problem consists of instantaneous or seasonal temperature variations in the outdoor air in asmuch as high outdoor temperatures impairs or makes the cooling more difficult. Furthermore, temperature variations arise as a consequence of varying power-extraction from the transformer.

OBJECTS AND FEATURES OF THE INVENTION

[0002] The present invention aims at obviating the above-mentioned problems by providing an installation by means of which the surplus energy from power transformers may be utilized in an economically useful way at the same time as the transformer may be cooled in an efficient way independent of seasonal or other variations in outdoor temperature. Thus, a primary object of the invention is to provide an energy utilization installation which, if required, enables direction of the surplus heat energy from a power transformer, either entirely or partly, to heat consumption units, such as radiators in dwelling-houses or other buildings, or entirely or partly to a heat accumulator. An additional object is to provide an installation suitable for the purpose, which is structurally simple and may be produced in an inexpensive way, in the main by the use of commercially available standard components.

[0003] According to the invention, at least the primary object is attained by the features defined in the characterizing clause of claim 1. Preferred embodiments of the installation according to the invention are furthermore defined in the dependent claims.

BRIEF DESCRIPTION OF THE APPENDED DRAWING

[0004] In the drawing:

[0005] FIG. 1 is a planar view of a transformer house, in which two transformers are included as well as an installation according to the invention,

[0006] FIG. 2 is an enlarged, schematic illustration of a heat pump included in the installation according to the invention, and

[0007] FIG. 3 is an enlarged, schematic detail A in FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

[0008] In FIG. 1, numeral 1 generally designates a house in which two transformers 2 are built-in. This house may consist of a small so-called network station of the type that is installed adjacent to residential districts or other houses with a limited size. The house 1 is divided in a number of compartments 3 by partition walls, which compartments are accessed individually via openings recessed in outer walls of the house, which openings may be closed by means of shutters or doors 4. The two transformers 2 are each installed in a compartment. In the other compartments, other forms of auxiliary equipment for transformers are installed, e.g. disconnecting switchers, collector rails, etc. In one of these compartment, a heat pump in its entirety designated 5, included in an installation according to the invention, is mounted.

[0009] In each individual transformer 2, a schematically illustrated cooling device generally designated 6 is included. Said cooling device may consist of a vessel filled with oil in which the core and the windings of the transformer are immersed. However, the cooling device may also be otherwise designed. The same may, for instance, consist of a hot air collecting space from which heat may be given off to another fluid than air via suitable heat exchangers.

[0010] Between the two transformers 2 and the heat pump 5, a first pipe system 7 extends in which a first heat carrying fluid may be circulated, more precisely in a feeder pipe 7′ and a return pipe 7″. As is seen in FIG. 1, one of the ends of each one of said pipes is connected to cooling devices 6 of the transformers via branch ducts 8′, 8″. The other end of each pipe 7′, 7″ is connected to a heat exchanger 9, e.g. a plate heat exchanger, placed near the heat pump 5. In practice, the pipe system 7 may consist of single pipe lines, which are connected to the oil vessels of the transformer cooling devices via the existing nipples which conventionally are used for filling oil in the vessels. In other words, in this case the heat carrying fluid in the pipe system 7 consists of the transformer's own cooling oil.

[0011] The above-mentioned pipe system 7 and the heat exchanger 9 have the purpose of enabling emission of heat to an evaporator 10 included in the heat pump 5, which evaporator in a known way via a second pipe system 11 communicates with a compressor 12, a condenser 13 as well as an expansion valve 14. The pipe system 11 and the components 10, 12, 13, 14 together form a closed pipe system in which a second fluid may be circulated in the usual way. Said second fluid consists of a conventional so-called cooling medium, e.g. of the type that contains propane, which can alternately be evaporated and condensed during absorption and emission, respectively, of heat.

[0012] A third pipe system 15, which includes a feeder pipe 15′ and a return pipe 15″, is with one end thereof connected to the heat emitting condenser 13 and with the opposite end thereof connected to one or more heat consumption units 16. Said units may consist of, for instance, radiators or other heat emitting devices in buildings of different types. The part of the pipe system 15, which is connected to the condenser 13, is illustrated schematically in the form of a coil of piping 17 which is inserted in the interior of the condenser. In practice, the condenser consists, however, most suitable of a plate heat exchanger. In the feeder pipe 15′, there is a pump 18 by means of which a heat carrying fluid, e.g. water or oil, can be circulated in the pipe system 15.

[0013] Furthermore, in the installation according to the invention, a fourth pipe system 19 is included, comprising two pipes 19′, 19″ which alternately may serve as a feeder pipe and a return pipe, respectively, depending on the functional state of the installation. Said pipe system is at least partly brought down in, for instance, rock, ground, or water in the form of a lake or a sea, the environment around the underground or submarine part of the pipe system—depending on the installation's functional state—serving either as a heat emitter (in the same way as in conventional so-called rock heat) or as a heat sink or accumulator. In FIG. 2, said combined heat accumulator and emitter, respectively, is schematically shown at 20.

[0014] In the shown embodiment, in which the first pipe system 7 is connected to a heat exchanger 9, the fourth pipe system 19 is connected to and integrated with a fifth pipe system 21 including first and second pipes 21′, 21″ outside the evaporator 10. The connection of the pipe system 21 to the evaporator is shown schematically in the form of a winding of piping 22, but also in this case, the evaporator consists of a plate heat exchanger. In a branch point between homologous pipes, in this case the pipes 19′ and 21′, in the two pipe systems 19, 21, a multi-port valve 23 is arranged of the type which not only may open and close but also throttle the flows in the respective pipes. In the pipe system 21, more precisely in the pipe 21′ between the multi-port valve 23 and the evaporator 10, a pump 24 is arranged. The two pipe systems 19 and 21 are integrated with each other so far that they contain one and the same fluid, preferably in the form of a so-called Brine liquid which, for instance, may consist of a mixture of spirit and water.

[0015] Adjustment of the multi-port valve 23 is carried out by means of a motor 25 which is driven electrically via an electric circuit schematically outlined with dash-dotted lines, in which a temperature sensor 26 in the feeder pipe 7′ of the first pipe system 7 is also included. In this connection, it should also be pointed out that a pump 27 to circulate the heat carrying fluid in the pipe system 7 is included in the return pipe 7″ of the pipe system 7.

[0016] In the preferred embodiment shown in the drawing of the installation according to the invention, a particular heat indicator 28 is connected to the heat consumption pipe system 15, e.g. a radiator co-operating with a fan, which radiator is located in, for instance, the compartment 3 in which the heat pump 5 is located. In all events, the heat indicator 28 should, however, be located inside the house. The heat indicator 28 is connected to the pipe system 15 via a sixth pipe system 29. More precisely, a feeder pipe in this pipe system is connected to the corresponding feeder pipe 15′ in the system 15 via a multi-port valve 30, which is adjusted by a motor 31. A certain part of the heat energy which is transported to the consumption unit 16 may, if required, be drawn off via the pipe system 29 and the heat indicator 28 with the purpose of heating the air in the interior of the house 1, particularly the air in the compartments 3 which are spaced-apart from the compartments for the transformers 2.

[0017] The Function and the Advantages of the Installation According to the Invention

[0018] Suppose that the installation is to work during the cold periods of the year and that the conventional so-called rock heat function of the heat pump 5 is turned on. In this state, the multi-port valve 23 keeps not only the feeder pipe 19′ from the underground heat emitter 20 open, but also the part of the pipe 21′ that extends between the valve and heat exchanger 9. This means that fluid (Brine-liquid) having a comparatively moderate temperature (e.g. about 0° C.) is mixed with warmer fluid from the heat exchanger 9, which in turn absorbs heat directly from the cooling devices 6 of the transformers 2 via the fluid circulating in the pipe system 7. Therefore, the liquid that is mixed in the multi-port valve 23 and then passes the evaporator 10 will have a considerably higher temperature than the liquid which is taken up from the underground via the feeder pipe 19′. Depending on varying temperatures in the underground as well as the cooling devices 6 of the transformers, the temperature varies, of course, in the evaporator 10, but in practice it may very well be within the range of +10 to +15° C. By the fact that the temperature of the fluid circulating through the evaporator may be considerably increased (in average from about 0° C. to +10° C.) the efficiency of the heat pump is radically improved, more precisely from a factor 3 (in the normal case) to a factor 5-7 or greater.

[0019] During the warm periods of the year, when the need for heating in buildings is low or non-existent, the heat pump may need to temporarily be put out of operation. Then, in order to still enable efficient cooling of the transformers, the multi-port valve 23 may be readjusted so that heat from the heat exchanger 9 is not utilized, per se, in the heat exchanger, but is led down into the underground (or to the submarine environment of the pipe system 19). This takes place by letting the pump 24 feed down the fluid in the pipe system 19 via the pipe 19′, which then acts as a feeder pipe, and then is brought in return to the pipe system 21 via the pipe 19″.

[0020] The advantages of the invention are obvious. When the need for heat to the consumption units during the cold season is high, surplus heat from the transformers 2 may be utilized for heating purposes in a very economic way at the same time as the cooling of the transformers becomes efficient. During the warm season, when the need for heating ceases, the installation may, by adjustment of the valve 23, simply be readjusted so that surplus heat from the transformers is led down underground or submarine, the heat energy being stored in the rock or the earth. The unit 20 then works as a heat accumulator from which stored energy may be recovered during the cold season (when the pipe system 19 is immersed in, e.g., sea or lake water, the water only serves as a heat sink). In other words, the installation according to the invention guarantees efficient cooling of the transformer or transformers in question irrespective of season, i.e. regardless if the heat pump needs to work for heating purposes or not.

[0021] Feasible Modifications of the Invention

[0022] The invention is not solely restricted to the embodiment described above and shown in the drawings. Thus, it is feasible to spare the particular heat exchanger between the first and fifth pipe systems, one and the same heat carrying fluid being circulated in the first, fourth and fifth pipe systems. As a heat carrying fluid in the pipe system connected to the transformer, it is also feasible to use another liquid (or gas) than oil. Furthermore, it should be pointed out that the installation's heat pump according to the invention does not necessarily have to be mounted in the same house as the transformer or transformers in question. Thus, the heat pump may also be installed in or near the building or the buildings to which the surplus heat energy from the transformer is to be transferred for heating purposes. In such cases, the first pipe system extends more or less long-range between the transformer house and the building or buildings in question. Neither need the above-mentioned consumption units to be installed indoors. Thus, the units may be placed outdoors (even underground) to simply emit heat energy. The installation then only serves to efficiently cool the transformer.

Claims

1. Installation to utilize surplus heat from a power transformer (2) of the type that includes a cooling device (6) for cooling the windings of the transformer, characterized in that a first pipe system (7) is connected to the cooling device (6) of the transformer for circulation of a first, heat carrying fluid between the cooling device of the transformer and a heat pump (5) with the purpose of enabling emission of heat to an evaporator (10) included in the heat pump, which in a known way via a second pipe system (11) containing a second heat carrying fluid communicates with a compressor (12), a condenser (13) and an expansion valve (14), that a third pipe system (15) having a third heat carrying fluid for transfer of heat to one or more consumption units (16) is connected to the condenser (13) of the heat pump, that a fourth pipe system (19) is directly or indirectly connected to the first pipe system (7), which fourth pipe system is partly brought down in a heat accumulator or emitter (20) in a rock, ground and/or water, and that a multi-port valve (23) acts between the first and fourth pipe systems (7, 19) for leading surplus heat from the cooling device (6) of the transformer via the first pipe system (7) to the evaporator (10) of the heat pump and/or to said heat accumulator (20).

2. Installation according to claim 1, characterized in that the first pipe system (7) is connected to a heat exchanger (9), which in turn is connected to the evaporator (10) of the heat pump (5) via a fifth pipe system (21), which communicates with the fourth pipe system (19) and contains the same heat carrying fluid as this, the multi-port valve (23) being arranged in a branch point between homologous pipes (19′, 21′) in said two pipe systems (19, 21).

3. Installation according to claim 1 or 2, characterized in that the same is located in one and the same house (1) as the transformer (2) and that a heat indicator (28) is connected to a feeder pipe (15′) in the third pipe system (15) for heating the air inside the house.