EP2525178A1 - Method for drying a solid isolation containing active section of an electric device which can be filled with impregnating oil and device for performing this method - Google Patents

Abstract

Water, contaminated impregnating and active portion of housing device after evacuation of housing is heated by condensation of solvent vapor which is formed by vaporizing solvent within and/or outside of housing. A mixed vapor flow is formed during heating, and water and solvent are separated. The heated active portion is dried under vacuum pressure, solid isolation of active portion is cooled and reheated by spraying heated spray oil on the surfaces of solid insulation. Thus, method for drying solid isolation containing active portion of electronic device is enabled. An independent claim is included for device.

Description

TECHNICAL AREA

The present invention relates to a method for drying an active part containing a solid insulating material of an electric device which can be filled with impregnating oil according to the introductory part of patent claim 1 and to an apparatus for carrying out this method.

With such methods, the active part of an electric device in the field can be dried and freed of old insulating oil, with which the housing of the device is filled during its operation in the field. The device is in particular a transformer, such as a power transformer, especially a so-called "shell type" transformer with disc windings, which are separated by insulation plates. The active part comprises solid insulation impregnated with insulating oil prior to operation of the electrical equipment (impregnating oil). The active part is installed in the vacuum-resistant housing of the device and kept at negative pressure.

There are methods in which the heat of condensation of a solvent vapor is used for rapid and gentle heating of the active part. The solvent vapor can be generated inside or outside the device housing. In this case, during the heating of the solid insulation leaking water in the form of a solvent and water vapor-containing mixed steam is fed together with unavoidable leakage of a condensation and separation device in which the condensed water separated from the solvent and the leakage air is sucked with a vacuum pump. The existing existing impregnating oil (waste oil) and / or impurities are removed by distillation from the solvent.

Furthermore, there are also processes in which heated spray oil is injected under vacuum over the active part of a transformer and this is heated. Here, only so much heated spray oil is filled into the lower part of the transformer that the solid insulation is not flooded. Subsequently, the spray oil is heated continuously and sprayed in the circulation process on the solid insulation. As a result, due to heating of the solid insulation moisture is evaporated from the solid insulation and sucked together with the spray oil vapor and existing air leakage with a vacuum system. Water vapor and oil vapors are condensed out in condensation plant.

STATE OF THE ART

A drying process of the type mentioned can the company publication MNV 46 / 1e. from the company Micafil Ltd, 8048 Zurich / Switzerland. A described in this prior art, working according to the Vapor phase method drying device for isolierölgetränkte insulations has a outside the transformer housing arranged Solventdampferzeuger with flexible solvent vapor lines between the evaporator and the transformer housing. The generated during the execution of the drying process in Solventdampferzeuger solvent vapor is passed through the flexible solvent vapor lines in a housing of a transformer and condensed to be dried and old insulating oil (waste oil) to be liberated solid insulation of the transformer active. In this case, the solid insulation is heated quickly and thus allows an effective discharge of water from the insulation. At the same time, the solvent removes the used oil from the insulation. Since the solvent vapor also condenses on the inner wall of the housing, this process requires a lot of energy and also requires a large apparatus, assembly and material costs in the field.

A drying method of the type mentioned is also in EP 1528342B1 described. A device shown in Figure 6 for carrying out a working according to the vapor phase method drying method for isolierölgetränkte solid insulation of a transformer has outside a housing of the transformer arranged on a Solventerhitzer and a feed pump. Solvent heated in the solvent heater is in circulation in liquid form in a lying within the transformer housing, guided in the manner of a venturi flow channel. When the heated, liquid solvent enters the flow channel, part of the solvent evaporates and condenses on the solid insulation to be dried and liberated from old insulating oil (waste oil) and thus promotes the escape of water from the insulation by rapid heating of the solid insulation. At the same time, the solvent removes the used oil from the insulation. Characterized in that the flow channel is formed in the manner of a Venturi nozzle and arranged as an open channel section in the interior of the housing, the circulation rate of a formed during heating of the solid insulation, solvent and water vapor mixed steam flow is greatly increased and are thus achieved short drying times.

Also in EP1 224 021 B1 the method of the type mentioned above and suitable for carrying out this method devices are described. In this prior art, the heated solvent is circulated in liquid form through expansion valves, expansion tank or evaporator into the transformer housing, where it flows directly to the heating of the active part of the transformer and partially evaporated. From the insulation washed out old insulating oil (waste oil) is circulated together with the solvent and occupied when flowing the active part whose surface again with the washed-out waste oil.

A method and associated apparatus for drying transformers in the field after the so-called oil-spray drying process is in the company publication MNV 50 / 3f Fa. Micafil SA, 8048 Zurich / Switzerland, entitled "Séchage de transformateurs par pulverization d'huile (Oil Spray) "described. With this technology, the transformer oil is emptied until the lowest insulation parts of the active part are no longer flooded with oil, then the transformer is kept under negative pressure and heated with an oil treatment plant in the circulation process, the oil and sprayed above on the active part and the insulation. The moisture evaporated from the insulation is sucked off with a vacuum pump and condensed in a condensation system. In the last phase of drying, the spray oil is emptied at the bottom of the transformer, the transformer continues to be under vacuum for so long held until the moisture in the insulation has fallen to acceptable levels. In this method, it takes a relatively long time until the internal insulation parts reach a minimum required temperature, since they come inadequate contact with the heated spray oil. In addition, since the achievable insulation temperatures are much smaller than in the Vapor Phase drying is achieved despite limited drying time and high energy consumption only limited drying results.

PRESENTATION OF THE INVENTION

The invention, as indicated in the claims, has for its object to provide a method of the type mentioned above, which is characterized by a low residual moisture content of the active part and a low energy requirement by a low residual moisture content of the solid part. At the same time it is also an object of the invention to provide a device which is suitable to carry out this method in a simple and economical manner.

According to the present invention, a process is provided for drying an active part containing a solid insulation of an electrical device that can be filled with impregnating oil. In this drying process, the at least water and contaminated impregnating oil containing and arranged in a housing of the device active part is heated after evacuation of the housing by condensation of solvent vapor, which is formed by a solvent which is evaporated inside and / or outside the housing. In this case, at least water and solvent are separated from a mixed steam stream formed during heating and, after the heating process has ended, the heated active part is kept at negative pressure for drying.

The solid insulation of the active part, which cools when it is heated to low pressure after completion of the heating process, is reheated by spraying warm spray oil onto the surfaces of the solid insulation. As a result, especially the outer parts of the solid insulation, which due to heat radiation and evaporation of solvent and moisture a Temperature reduction suffered, again heated. As a result of the increased temperature of the solid insulation, any remaining solvent and residual moisture remaining in these isolations are evaporated off efficiently. This considerably shortens the drying process and thus not only reduces the throughput time but also the energy requirement of the drying process according to the invention. In addition, at the bottom of the housing usually remaining, dissolved out of the solvent from the active part old impregnating oil is diluted by the spray oil used for reheating. The temperature increase of the solid insulation achieved by reheating with the heated spray oil ensures that the solvent and water are now removed much more quickly from the solid insulation than in a prior art drying process in which such after-heating is not provided. In addition, the entire drying process can be carried out without expensive thermal insulation of the housing.

• das ins Gehäuse eingeleitete Sprayöl wird aus dem Gehäuse abgepumpt,
• das abgepumpte Sprayöl wird ausserhalb des Gehäuses erwärmt,
• das erwärmte Sprayöl wird ins Gehäuse geführt und auf die Oberfläche der Feststoffisolationen gesprüht, und
• das versprühte Sprayöl wird nach Abgabe von Wärme an die Feststoffisolationen
• im Gehäuse gesammelt und zum Umwälzen wieder aus dem Gehäuse abgepumpt, und können nach Beendigung des Umwälzverfahrens und Entfernen des Sprayöls aus dem Gehäuse die nachgeheizten Feststoffisolationen zum Trocknen weiterhin auf Unterdruck gehalten werden.

In a preferred embodiment of the method, the spray oil can be introduced into the housing before it is heated below the solid insulation, and the following method steps can be carried out in a circulation process following the introduction of the spray oil into the housing:

• the spray oil introduced into the housing is pumped out of the housing,
• the pumped-off spray oil is heated outside the housing,
• the heated spray oil is introduced into the housing and sprayed onto the surface of the solid insulation, and
• the sprayed spray oil turns to the solid insulation after release of heat
• collected in the housing and pumped out of the housing again to circulate, and after completion of the circulation process and removing the spray oil from the housing, the reheated solid insulation for drying can be kept at negative pressure.

In this preferred embodiment, after drying at the bottom of the housing possibly remaining, washed out by the solvent from the solid insulation old impregnating oil (waste oil) only small proportions of solvent, since any still existing solvent when circulating together with the collected at the bottom of the housing spray oil is pumped off as a mixture and this mixture is heated outside the housing and then sprayed onto the solid insulation in the housing. During the spraying process, the remaining solvent evaporates and the proportion of solvent in the used oil is reduced considerably.

In order to improve the mode of action of the abovementioned embodiment of the method according to the invention, in particular with regard to a short throughput time and reduced energy consumption with low residual moisture content of the solid insulation, the solid insulation which cools when held to negative pressure can be reheated at least a second time by spraying heated spray oil become. By the two resp. repeated repeating the reheating of the solid insulation is at the bottom of the generally not completely emptied housing collecting mixture of spray oil and old impregnating oil is further diluted so that the waste oil content drops to advantageously small values.

In procedurally advantageous manner, the spray oil needed for spraying can be sucked into the housing before being heated by the negative pressure.

A particularly good heat transfer from the heated spray oil to the solid insulation to be reheated is achieved when the spray oil is sprayed mainly from above and / or from the side of the solid insulation.

An additional increase in the efficiency of the inventive method is achieved when the solvent is heated outside the housing and is injected into a arranged in the interior of the housing flow channel. In this case, the flow channel is advantageously oriented in such a way that a flow containing solvent vapor during injection of the heated solvent is directed into a free space lying between the inner wall of the housing and the solid insulation.

After completion of the reheating for definitive filling of the housing provided impregnating oil can be heated and degassed with a device provided for performing this method device outside the housing.

The apparatus provided for carrying out the method according to the invention may comprise, in addition to the housing receiving the active part, a vacuum system connected to the interior of the housing, a solvent steam generator arranged inside or outside the housing and a condensation device arranged outside the housing, which is connected to the interior of the housing. contain and an oil spray system with a provided inside the housing spray nozzle assembly and a pump for conveying the heated outside the housing spray oil into the spray nozzle assembly.

The oil spray system may further comprise an air-cooled device preceding the condensation device for separating spray oil and / or for condensing solvent vapor.

Air heated in the air cooled device may be routed to an outer wall of the housing formed as a bottom. The heat radiation of the housing can be reduced and energy saved accordingly.

The solvent steam generator can be arranged within the housing and have a flow channel configured in the manner of a Venturi nozzle and a solvent distribution channel receiving the externally supplied, heated solvent with solvent injection openings which are guided into the flow channel. The solvent injection ports may be oriented so that a solvent-vapor-containing flow formed on exit from the ports is directed into a clearance between the inner wall of the housing and the solid insulation.

The drying device can also have a heater which heats the outside of the housing and can be connected to the solvent evaporator, which can be connected to the oil spray system after the solvent supply has been interrupted.

The oil spray system may comprise a heater upstream of the device for degassing the impregnating oil. This is the use of an additional Oil preparation plant is not necessary and it saves operating costs and investment.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1

eine erste Ausführungsform einer Trocknungsvorrichtung, in der das erfindungsgemässe Verfahren zur Trocknung der Feststoffisolationen eines mit Imprägnieröl füllbaren elektrischen Gehäuses durchgeführt wird,

Fig.2

eine gegenüber der erste Ausführungsform ergänzte zweite Ausführungsform der Trocknungsvorrichtung, die zusätzlich eine Ölentgasungsstufe sowie einen Öllagertank für das Imprägnieröl aufweist, und

Fig.3

ein Diagramm, in dem der Verlauf wesentlicher Verfahrensparameter des erfindungsgemässen Verfahrens, wie der Druck im Gehäuse des elektrischen Gerätes und die Temperatur der Feststoffisolation während der verschiedenen Prozessphasen dargestellt sind.

With reference to drawings, the invention will be explained in more detail below. Hereby shows:

Fig.1

a first embodiment of a drying apparatus in which the inventive method for drying the solid insulation of an impregnated with impregnating oil electrical housing is performed,

Fig.2

a comparison with the first embodiment supplemented second embodiment of the drying device, which additionally has a Ölentgasungsstufe and an oil storage tank for the impregnating oil, and

Figure 3

a diagram in which the course of significant process parameters of the inventive method, such as the pressure in the housing of the electrical device and the temperature of the solid insulation during the various stages of the process are shown.

WAYS FOR CARRYING OUT THE INVENTION

In all figures, like reference numerals designate like-acting parts. The in the FIGS. 1 and 2 Drying devices shown serve the drying of a solid 1.1 containing active part 1.1 of a designed as a transformer electrical device in the vacuum-tight running housing. 1

To heat the active part 1.1 can be heated in a heater 4 either solvent or spray oil. The solvent is generally a light oil having a much higher boiling point than water and a much lower boiling point than, if necessary, still in the solid insulation 1.5 existing impregnating oil, with which the housing 1 of the transformer is filled during its operation, and which is removed from the transformer housing 1 prior to drying of the active part 1.1. The solvent necessary for the heating of the active part 1.1 is fed from a solvent storage tank 9 via a shut-off valve 20.2 with a feed pump 8, a shut-off valve 20.3, a solvent feed line 4.2.1 to the solvent / oil heater 4. The heated solvent is passed via a shut-off valve 20.10 through a cover flange 1.3 to a disposed within the transformer housing 1 Solventverteilkanal 5 with injection ports 5.1. When heated solvent flows into a flow channel 6, it partially evaporates. The Solventverteil- 5 and the flow channel 6 therefore act more or less as an evaporator.

The solvent distribution channel 5 can be advantageously formed from exposed tubes with at least one of the injection openings 5.1 and / or injection nozzles. In the region of the injection openings 5.1, the narrowest cross-section is in the manner of a Venturi nozzle designed flow channel 6, which can be performed for cost reasons and ease of installation in the transformer housing 1 as Venturi tube. In this case, the flow channel 6 is directed so that an emerging from the flow channel 6 and possibly still solvent and waste oil contained solvent vapor flow exiting into the free space between the transformer housing 1 and active part 1.1.

From the heater 4, an unspecified connection line leads to an oil shut-off valve 20.17. This valve is connected via a guided through a cover flange 1.3 oil connection line 4.3 with oil spray nozzles 2, which are arranged in the transformer housing 1. The oil spray nozzles 2 are directed so that used for oil spraying insulating oil, hereinafter called spray oil, sprayed substantially the entire upper part of the active part 1.1.

The transformer housing 1 has at the bottom in its bottom a drain opening 1.4 for condensed solvent, as well as optionally washed by the solvent from the solid insulation waste oil as well as the spray oil. The drain opening 1.4 is connected via a shut-off valve 20.8, a drain tank 7 and a shut-off valve 20.1 with a feed pump 8. The outlet of the feed pump 8 is connected via a shut-off valve 20.3 with the solvent / oil heater. 4 connected or alternatively via a shut-off valve 20.5 with a spray oil tank 3 or alternatively via a shut-off valve 20.6 with a Solventvorratstank 9 or via a check valve 20.7 with an oil tank 19 for receiving the possibly existing waste oil, which during drying of the transformer active 1.1 by the solvent from the solid 1.5 was removed and subsequently separated by distillation from the solvent.

The transformer housing 1 is connected via a first mixing steam leading line 10, a Dampfabsperrventil 20, an air-cooled condenser / separator 11 and a mixed steam condenser 16 with a vacuum system 18. The mixed steam condenser 16 has two discharge nozzles, one of which is connected to the vacuum system 18 and the other via a vacuum shut-off valve 21 controlling the emptying of solvent and water with a separating container 17 containing a water drain valve 22.

The air-cooled condenser / separator 11 has a connection to the air supply from a fan 11.2 and a further connecting piece, through which the heated air is guided via a hot air line 11.3 to the bottom of the transformer housing1. Any condensed solvent / oil vapor is fed via drain port 11.5, Solvent / OI-Abtropfleitung 11.6 and check valve 20.9 the drain tank 7.

At the Fig.2 apparent second embodiment of the drying device an impregnating oil tank 13, a Ölentgasungstufe 14 and an oil feed pump 15 are additionally provided. By means of this additional means, the transformer can be additionally filled with degassed impregnating oil after drying in the field with minimal expenditure on equipment. The tank 13 is connected to the oil degassing stage 14 via line 13.1, oil shut-off valve 20.11, feed pump 8, shut-off valve 20.3, solvent / oil heater 4 and oil shut-off valve 20.15. The heated and degassed impregnating oil is introduced into the transformer housing 1 with the pump 15 via an oil shut-off valve 20.13 and the shut-off valve 20.8. The permissible oil level in the transformer housing 1 is monitored by means of a level switch 12.1.

• Zunächst werden mit der Vakuumanlage 18 bei geöffnetem Dampfabsperrventil 20 und geöffnetem Absperrventil 20.8 das Transformatorgehäuse 1, der luftgekühlte Kondensator/Abscheider 11, der Mischdampfkondensator 16 und der Ablaufbehälter 7 evakuiert. Zugleich wird vom Solventvorratstank 9 eine genügende Menge Solvent über das Absperrventil 20.2, die Solventzuführleitung 4.2 und das Absperrventil 20.1 in den Ablaufbehälter 7 mittels Druckdifferenz eingesaugt und mit dem Füllstandsindikator 7.1 überwacht. In einer nun folgenden aus Fig.3 ersichtlichen Aufheizphase wird das im Ablaufbehälter 7 vorhandene Solvent via Absperrventil 20.3 und Solventverbindungsleitung 4.2.1 mit der Förderpumpe 8 dem Solvent/Ölerhitzer 4 zugeführt, auf eine etwas oberhalb einer vorgegebenen Trocknungstemperatur liegende Temperatur erhitzt und via Absperrventil 20.10 durch den Abdeckflansch 1.3 zu dem innerhalb des Transformatorgehäuse 1 angeordneten Solventverteilkanal 5 gepumpt und durch die Einspritzöffnungen 5.1 in dem Strömungskanal 6 versprüht.

The mode of action of the drying method according to the invention and the device provided for carrying it out according to the invention are as follows:

• First, the transformer housing 1, the air-cooled condenser / separator 11, the mixed steam condenser 16 and the drain tank 7 are evacuated with the vacuum system 18 with the steam shut-off valve 20 open and the shut-off valve 20.8 open. At the same time, the solvent supply tank 9 draws in a sufficient amount of solvent through the shut-off valve 20.2, the solvent supply line 4.2 and the shut-off valve 20.1 into the drainage tank 7 by means of a pressure difference and monitors it with the filling level indicator 7.1. In a now following off Figure 3 apparent heating phase, the existing in the drain tank 7 Solvent via shut-off valve 20.3 and 4.2.1 Solvent connection line with the pump 8 supplied to the solvent / oil heater 4, heated to a temperature slightly above a predetermined drying temperature and via shut-off valve 20.10 through the cover 1.3 to the within the Transformer housing 1 arranged Solventverteilkanal 5 pumped and sprayed through the injection openings 5.1 in the flow channel 6.

The heated solvent is at a higher pressure when heated. When the solvent exits the injection openings 5.1, the pressure in the solvent drops sharply, with some of the heated solvent evaporating while cooling down by the amount of its heat of vaporization. The resulting solvent vapor condenses on the active part 1.1 and heats it with simultaneous evaporation of the water contained in the solid insulation 1.5, resulting in the formation of a solvent and steam containing mixed steam with a small amount of air leakage in the transformer housing 1. This mixed steam is sucked off with the vacuum system 18 via Dampfabsperrventil 20, any oil vapor and oil drops are deposited in the air-cooled condenser / separator 11 and condensed solvent and water vapor in the mixed steam condenser 16. The condensate flows via Vakuumabsperrventil 21 to the separation tank 17. The separate solvent is fed back to the solvent circuit with the feed pump 8.1 via shut-off valve 20.4 and heated in the solvent / oil heater 4. The separated water is discharged via the water drain valve 22. Solvent condensate obtained in the transformer housing 1 and possibly containing waste oil flows via the drain opening 1.4 and the open shut-off valve 20.8 to the drain tank 7 and is supplied to the feed pump 8 via the solvent / oil heater 4 for evaporation back to the Solventverteilkanal 5 respectively the Solventeinspritzöffnungen 5.1.

If the level of solvent in the drain tank 7 drops too low, additional solvent is sucked in via the shut-off valve 20.2 from the solvent storage tank 9 until the filling level indicator 7.1 is flooded again.

The solvent is injected through the solvent injection openings 5.1 with advantage at the narrowest point in the flow channel 6. This results in a particularly high flow velocity and a correspondingly high negative pressure. This leads to a jet effect, through which the mixed steam present in the transformer housing 1 is sucked into the flow channel 6. The drawn-in mixed steam mixes with the high-speed injected solvent and the solvent vapor formed during injection. This produces the advantageous effect that, on the one hand, rapid and accurate temperature control of the solvent vapor entering the transformer housing 1 is achieved, and, on the other hand, that the mixed steam at increased speed flows around the active part 1.1 present in the transformer housing 1 turbulently by sucking in the mixed steam into the flow channel 6.

Due to the arrangement of at least one flow channel 6 in such a way that the exiting solvent vapor flows into the existing free space between the active part 1.1 and the inner wall of the transformer housing 1, a solvent vapor flow of high speed arises within the transformer housing 1, which the active part 1.1 everywhere with turbulent, almost flows evenly Solventdampfströmung, whereby a uniform heating of the active part 1.1 is significantly accelerated.

Since the solid insulation 1.5 of the active part 1.1 possibly still contain waste oil, this is washed out by the condensing solvent and mixed with the solvent to a solvent / oil mixture.

Upon reaching a minimum temperature of the solid insulation 1.5, the periodic Solventzuführung via shut-off valve 20.2 is interrupted, that is Shut-off valve 20.2 closed and one off Figure 3 apparent phase D is initiated, in which the solvent / oil mixture is circulated as described above, wherein mixed steam is removed continuously. Since the oil content in the flow channel 6 does not evaporate, with continuous removal of mixed steam from the transformer housing 1 and condensation of the extracted mixed steam in the air-cooled condenser / separator 11 and mixed steam condenser 16, the waste oil content in the transformer housing 1 steadily increases until practically only pure waste oil is present , This oil is emptied with the feed pump 8 during phase D via shut-off valve 20.7 in the oil tank 19.

After that, in one Figure 3 apparent phase H2 through the Solventeinlaßventil 20.2, the feed pump 8, the solvent / Ölerhitzer 4, the now open shut-off valve 20.10 and the Solventeinspritzöffnungen 5.1 again introduced solvent in the transformer housing 1 and circulated in the aforementioned manner and evaporated.

Once the solid insulation 1.5 are heated to a temperature sufficient for drying, resp. to wash out any existing waste oil, can again (in Figure 3 not shown) are introduced phase D, in which, as described above, without feeding of solvent, the solvent / oil mixture circulated and then any existing existing impregnating oil is emptied.

In one Figure 3 apparent, introduced by switching off the feed pump 8 phase V1 of the existing in the transformer housing 1 mixing steam is supplied to the air-cooled condenser / separator 11 and the mixed steam condenser 9. Eventually entrained oil vapors are deposited in the air-cooled condenser / separator 11 through the separators / baffles. By means of condensation of solvent and water vapor in the mixed steam condenser 16, the pressure in the transformer housing 1 is lowered to such a low level until a large part of the moisture and the solvent content in the solid solution 1.5 has evaporated.

During phase V1, the solid insulation 1.5 cools due to evaporation of moisture and solvent from the Feststoffisolation1.5 and heat radiation of the Active part 1.1 and the transformer housing 1 to the environment from so far that the evaporation of moisture and solvent due to low temperature of Feststoffisolation1.5 is greatly reduced.

In one Figure 3 apparent phase OF, the transformer housing 1 is maintained in the manner previously described as in the phase V1 to negative pressure. Thereafter, due to pressure difference between the transformer housing 1 and 3 spray oil tank spray oil from the tank 3 via Ölabsperrventil 20.16, oil filter 3.2, spray oil 3.1, Ölabsperrventil 20.14, and check valve 20.8 fed into the transformer housing 1 until the lower level switch 12 is flooded.

In one Figure 3 apparent phase OS, the spray oil via shut-off valve 20.8, drain tank 7 and shut-off valve 20.1 of the feed pump 8 is supplied and then promoted via shut-off valve 20.3 and 4.2.1 Solventverbindungsleitung in the solvent / Öhler 4. In the heater 4, the spray oil is heated to a value slightly above the insulation temperature and passed via shut-off valve 20.17 and oil connection line 4.3 to the arranged within the transformer housing 1 spray oil nozzles and sprayed over the surface of the active part 1.1. As a result, the temperature of the solid insulation 1.5 increases again to such values that the residual solvent and moisture evaporates from the solid insulation 1.5. The present in the transformer housing 1 solvent / water vapor mixture is sucked in the same manner as previously described in the phase H1 of the vacuum system 18. Any existing oil vapors and oil drops are deposited in the air-cooled condenser / separator 11 and fed back via solvent / Ölabtropfleitung 11.6 and shut-off valve 20.9 the oil circuit.

In order to lower the pressure in the transformer housing 1 to lower values than can be achieved during the oil spray drying, is in the Figure 3 apparent phase V2, the oil circulation respectively the oil spraying interrupted and the existing in the transformer housing 1 oil largely with the feed pump 8 via shut-off valve 20.5 emptied into the oil tank 3. Thereafter, during the phase V2 by the lower pressure in the transformer housing 1 and the elevated temperature of the solid insulation 1.5, the evaporation of the water and the solvent from accelerates the solid insulation 1.5 again, thereby achieving shorter drying times and smaller moisture and solvent contents in the solid insulation 1.5.

By repeated filling of spray oil in the transformer housing 1 and oil spraying with heated oil in the manner previously described with subsequent phase V2, the temperature of the insulation 1.5 can be repeatedly increased to the desired values and an optimal drying quality can be achieved. By repeated repetition of oil depletion and oil sprays the respectively at the bottom of the normally not completely emptied transformer housing 1 accumulating and washed out of the active part 1.1 old impregnating oil is diluted so much that no negative properties in the replenishment of the transformer housing 1 with processed oil longer exist.

In the embodiment of the drying device according to Fig. 2 is in addition to the under Fig.1 described procedure, that is, after completion of the drying process, the housing 1 containing the built-active part 1.1 filled with conditioned insulating oil (impregnating oil). For this purpose, the apparatus, in particular the vacuum system 18, the solvent / oil heater 4 and the feed pump 8, can advantageously be used for filling the impregnating oil. The vacuum system 18 remains, as described above, connected via the open Dampfabsperrventil 20 with the transformer housing 1 and keeps the active part 1.1 under vacuum. In addition, the degassing stage 14 is held on the vacuum connection line 4.4 and the open Vakuumabsperrventil 21.1 with the vacuum system 18 to negative pressure. From Impregnating oil tank 13 is fed via Impregnating oil line 13.1 and Ölabsperrventil 20.11 Impregnating the pump 8 and then promoted via shut-off valve 20.3 to the solvent / oil heater 4, heated and pumped via Ölabsperrventil 20.15 in the Ölentgasungsstufe 14 and degassed there. The degassed impregnating oil is introduced via the oil shut-off valve 20.13, shut-off valve 20.8 and drain opening 1.4 into the vacuum-standing transformer housing 1 with the oil feed pump 15 until the maximum permissible oil level according to the oil level switch 12.2 has been reached.

LIST OF REFERENCE NUMBERS

1

Housing, transformer housing

1.1

active part

1.2

housing openings

1.3

covering flange

1.4

drain hole

15

Solid insulation

2

Spray oil jets

3

Spray oil tank

3.1

Sprayölzuführleitung

3.2

oil filter

3.3

Spray oil return line

4

Solvent / oil heater

4.1

Solvent connecting line

4.2; 4.2.1

Solventzuführleitungen

4.3

Oil connection line

4.4

Vacuum connection line

5

Solvent distribution channel (pipe)

5.1

Solvent injection holes

6

StrömungskanalNenturirohr

7

drain tank

7.1

level indicator

8; 8.1

feed pumps

9

Solvent supply tank

10

Mixing steam line

11

air-cooled condenser / separator

11.1

Separate baffles

11.2

fan

11.3

Hot air line

11.4

Outlet opening mixing steam

11.5

Outlet solvent condensate

11.6

Solvent / oil drip line

12

Oil level switch (below)

12.1

Oil level switch (above)

13

Imprägnieröltank

13.1

Imprägnieroelleitung

14

Ölentgasungsstufe

15

Oil pump

15.1

oil line

16

Mixing steam condenser

17

separation vessel

18

vacuum system

19

oil tank

20

Dampfahsperrventil

20.1-20.10

Shut-off valves

20:11 to 20:17

Ölabsperrventile

21,21.1

Vakuumabsperrventile

22

Water drain valve

H1, D, H2, V1, OF, OS and V2

temporally successive phases in the drying process

Claims (15)

Process for drying an active part (1.1) containing solid insulation (1.1) of an electrical device which can be filled with impregnating oil, in which the active part (1.1) containing at least water and contaminated impregnating oil and arranged in a housing (1) of the device is evacuated after evacuation of the housing (1) is heated (phases H1, H2) by condensation of solvent vapor, which is formed by a solvent which is evaporated inside and / or outside of the housing (1), in which at least formed water and solvent from a mixed steam formed during heating are, and in which after completion of the heating process, the heated active part (1.1) is kept to negative pressure for drying (phases V1, V2), characterized in that after completion of the heating process when holding on vacuum cooling solid insulation (1.5) of the active part (1.1) by spraying heated spray oil on the surfaces of the solid rehabilitation (5.1) (Phase OS). Method according to claim 1, characterized in that
that the spray oil is introduced into the housing (1) before its heating below the solid insulation (1.5) (Phase OF),
the following method steps are carried out in a recirculation method following the introduction (phase OF) of the spray oil into the housing (1): the spray oil introduced into the housing (1) is pumped out of the housing (1), the pumped-off spray oil is heated outside the housing (1), the heated spray oil is fed into the housing (1) and sprayed onto the surface of the solid insulation (1.1), and the sprayed spray oil is collected after release of heat to the solid insulation (1.5) in the housing (1) and pumped out of the housing (1) to circulate, and that after completion of the circulation process and removal of the spray oil from the housing (1), the reheated solid insulation (5.1) for drying are kept at negative pressure (phase V2). A method according to claim 2, characterized in that the holding on negative pressure cooling solid insulation (1.5) are heated by spraying heated spray oil at least a second time (Phase OS). Method according to one of claims 2 or 3, characterized in that the spray oil during introduction (phase OS) by the negative pressure in the housing (1) is sucked. Method according to one of claims 1 to 4, characterized in that the heated spray oil is sprayed mainly from above and / or from the side of the solid insulation (1.5). Method according to one of claims 1 to 5, characterized in that the solvent is heated outside the housing (1) and in a in the interior of the housing (1) arranged flow channel (6) is injected. A method according to claim 6, characterized in that the flow channel (6) is aligned so that when injecting the heated solvent forming, solvent-containing flow in a between the inner wall of the housing (1) and the solid insulation (1.5) lying free space is directed. Method according to one of claims 1 to 7, characterized in that after completion of the reheating (phase OS) for the definitive filling of the housing (1) provided impregnating oil outside the housing (1) is heated and degassed. Apparatus for carrying out the method according to one of claims 1 to 8, comprising in addition to the active part (1.1) receiving housing (1) also connected to the interior of the housing (1) vacuum system (18), inside or outside of the housing (1 ) arranged Solventdampferzeuger (5, 6) and a outside of the housing (1) arranged condensation device (16) which is connected to the interior of the housing (1), characterized in that the device further comprising an oil spray system comprising a spray nozzle arrangement (2) provided in the interior of the housing (1) and a pump (8) for conveying the spray oil heated outside the housing (1) into the spray nozzle arrangement (2). Apparatus according to claim 9, characterized in that the oil spray system further comprises a condensing device (16) upstream air-cooled device (11) for separating spray oil and / or for condensing solvent vapor. Apparatus according to claim 10, characterized in that in the air-cooled device (11) heated air is guided on an outer wall formed as a bottom of the housing (1). Device according to one of claims 9 to 11, characterized in that the solvent steam generator (5, 6) within the housing (1) is arranged and designed in the manner of a Venturi nozzle flow channel (6) and the externally supplied, heated solvent receiving Solventverteilkanal (5) having Solventeinspritzöffnungen (5.1), which are guided in the flow channel (5). Apparatus according to claim 12, characterized in that the Solventeinspritzöffnungen (5.1) are aligned so that when emerging from the openings (5.1) formed, solvent-containing flow in a lying between the inner wall of the housing (1) and the solid insulation (1.1) free space is addressed. Device according to one of Claims 9 to 13, characterized in that the drying device has a heater (4) which heats the solvent outside the housing (1) and can be connected to the solvent evaporator (5, 6), which can be connected to the oil spray system after the solvent supply has been interrupted is. Device according to one of claims 9 to 14, characterized in that the oil spray system comprises a heater (4) upstream device (14) for degassing the impregnating oil.

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