EP3029403B1 - Method and device for drying the solid insulation of the active section of an electrical device using the vapour-phase method - Google Patents

Description

TECHNICAL AREA

The present invention relates to methods according to the introductory part of claim 1 and to an apparatus according to the introductory part of claim 8 for carrying out this method.

With the aforementioned method, the solid insulation of the active part in the housing of the electrical device, typically a transformer, can be dried, but possibly also in a stationary autoclave. In particular, a newly delivered transformer can be dried at the site before filling with insulating oil. But it can also dried the active part of an electric device in the field and the solid insulation of old insulating oil are released, with which the housing of the transformer is filled during its operation in the field. The active part includes, among other solid insulation, which are flooded with insulating oil before the operation of the transformer. The active part is installed in the vacuum-resistant housing of the transformer and kept at negative pressure during the process.

There are methods in which, for the purpose of drying, heated insulating oil is distributed under vacuum over the active part of a transformer and this is heated. Here, only so much heated insulating oil is poured into the lower part of the transformer that the solid insulation is not flooded. Subsequently, the insulating oil is heated and distributed in the circulation process on the solid insulation until the desired drying temperature is reached. As a result of heating the solid insulation under vacuum moisture is evaporated from the solid insulation and sucked together with the existing air leakage through a vacuum system and condensed water vapor in a condenser.

Furthermore, there are also processes which exploit the heat of condensation of solvent vapor for rapid heating of the active part. The solvent vapor may alternatively be generated inside or outside the transformer housing. The water vapor emerging from the solid insulation during heating and the solvent vapor present in the transformer housing are fed, together with the unavoidable leakage air, to a condensation and separation device in which the condensed water is separated from the condensed solvent and the leakage air is sucked off with a vacuum pump. The washed out of the solid insulation old impregnating oil is removed by distillation from the solvent.

Furthermore, there are processes in which the heating in a first phase is achieved by condensation of solvent vapor and in a second phase by circulation and spraying of heated Isolieroel on the active part. The water vapor exiting from the insulation is fed together with the solvent / oil vapor to a condensation device, thereby condensing and sucking the leakage air with a vacuum pump.

STATE OF THE ART

A drying process of the type mentioned in the introduction and the suitable apparatus for carrying out this process are disclosed in US Pat EP 1528342 B1 described. An in Figure 6 apparatus for carrying out a working according to the vapour-phase method drying method for isolierölgetränkte solid insulation of a transformer has arranged outside a housing of the transformer, a solvent heater and a feed pump. Solvent heated in the solvent heater is guided in liquid form in the circulating process into a flow channel located inside the transformer housing and designed in the manner of a Venturi nozzle. 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 through the solvent, the used oil dissolved out of 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, resulting in good heat transfer to the transformer active part.
For transformers with a relatively small drain / drain, however, only reduced amounts of heated solvent can be pumped out of the transformer housing and injected into the flow channel. As a result, the heating power of the apparatus is greatly reduced, resulting in extended drying times.

Another drying method according to the vapour-phase method describes EP 1 224 021 B1 , 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. For transformers with a relatively small drain / drain port, only reduced amounts of heated solvent can be circulated, and injected through the expansion valves. As a result, the heating power of the apparatus is greatly reduced, resulting in long drying times and insufficient drying temperatures.

PRESENTATION OF THE INVENTION

The invention, as indicated in the claims, has the object to increase the efficiency and efficiency of the method of the type mentioned above and at the same time to provide a device which is suitable to perform this method in a simple and economical manner.

1. (a) der erste Solventsattdampfstrahl,
2. (b) durch die erste Einsaugöffnung (3.1) eingesaugter Mischdampf,
3. (c) durch eine zweite Einsaugöffnung (3.2.1) eingesaugter Mischdampf (3.10) und
4. (d) der zweite Solventsattdampfstrahl.

According to the present invention, a process for drying the water, optionally additionally containing insulating oil and impurities Solids isolation of the active part of an electrical device provided by the Vapor - Phase method. In this process, the active part is heated by condensation of Solventsattdampf in at least one subsequent pressure reduction phase thereby accumulating, at least solvent and steam-containing mixed steam by condensation from a the active part receiving vacuum vessel with superheated solvent to produce a Solventsattdampfstrahls is vaporized in a flow channel having at least one arranged in the vacuum container first intake opening and a vacuum vessel arranged in the outlet opening. A first part of the superheated solvent is injected into at least a second Solventsattdampfstrahls in at least a second portion of the flow channel generating a first Solventsattdampfstrahls in a first and a remaining second of the heated solvent, wherein at the production of the second Solventsattdampfstrahls the flows listed below the same Flow direction have:

1. (a) the first solvent steam jet,
2. (b) mixed steam drawn in through the first suction opening (3.1),
3. (c) through a second suction port (3.2.1) sucked mixed steam (3.10) and
4. (D) the second Soldenssattdampfstrahl.

The multi-stage injection of the superheated solvent into a plurality of suitably connected evaporator stages in the flow channel increases the turbulence of the Solventsattdampfs generated in the evaporator stages and the sucked mixed steam at the exit from the flow channel in the vacuum vessel. Therefore, the solid insulation of the active part can be heated more rapidly and more uniformly and thus the drying time can be shortened and the quality of the drying can be improved. By injecting the heated solvent at high speed in several stages, the resulting Solventsattdampf mixed with the supplied from the vacuum tank and sucked through the inlet openings of the flow channel mixed steam. As a result, in addition to the short and uniform heating of the solid insulation and an accurate Monitoring of the solvent vapor temperature and an increased flow velocity of the solvent vapor ensured.

Advantageously, the superheated solvent is heated to a temperature which is above the permissible drying temperature and below the ignition point of the solvent. With such a high solvent temperature, the majority of the supplied, superheated solvent vaporizes to Solventsattdampf in the multistage Solventdampferzeugung. This has the advantage that only slightly unvaporated solvent is discharged through a discharge nozzle from the vacuum tank and even with vacuum tanks, which are designed as a transformer housing and have only small emptying nozzle, large evaporator heating and thus a particularly high efficiency of the method is achieved according to the invention.

In one embodiment of the method in which the vacuum container consists of an active part receiving transformer housing and a steam generator housing, which is attached to a housing opening to the transformer housing and which receives the flow channel, the non-evaporated solvent and optionally existing insulating oil between the outlet opening of the flow channel and the opening of the transformer housing from a discharged at the outlet opening from the flow channel steam jet and removed from the evaporator housing

In one embodiment of the method in which the first and the second portion of the flow channel are each in the manner of a Venturi nozzle, the first part of the superheated solvent at a constriction of the first portion and the second part of the superheated Solövents at a constriction of the second portion be injected into the flow channel. This ensures that only on the active part condensed solvent must be removed via a drain pipe from the transformer housing. A large part of non-evaporated solvent and possibly existing waste oil is removed from the vacuum tank in the evaporator housing. As a result, the discharge nozzle is relieved and can therefore be sized small. It is so despite large drainage a large circulation of solvent and possibly existing waste oil allows, which ensures high performance of the solvent evaporator.

During the pressure reduction phase resulting solvent and optionally resulting insulating oil can be removed due to gravity or pressure difference from the vacuum tank and after overheating the solvent can be injected back into the flow channel.

Optionally incurred, at the end of the pressure reduction phase still in the vacuum tank existing insulating oil can be removed due to gravity or a pressure difference between the vacuum tank and a drain tank from the vacuum tank.

When carrying out the process according to the invention, in a fine vacuum phase subsequent to the pressure reduction phase, the superheated solvent can be injected into the flow channel to form superheated solvent vapor so as to increase the efficiency during reheating and accordingly during drying in the fine vacuum phase.

1. (a) der erste Solventsattdampfstrahl,
2. (b) durch die erste Einsaugöffnung eingesaugter Mischdampf,
3. (c) durch eine zweite Einsaugöffnung eingesaugter Mischdampf und
4. (d) der zweite Solventsattdampfstrahl.

According to the present invention, a device is also provided for carrying out the method according to the invention, which contains a vacuum container for receiving a water, optionally additionally insulating oil and impurities containing solid insulation of the active part of an electrical device and in each case communicating with the vacuum container: a vacuum system,
a device for heating solvent,
a arranged in the vacuum vessel solvent steam generator with a flow channel having at least one arranged in the vacuum container first intake opening and a vacuum vessel arranged in the outlet opening, and
a condensation device for sucking mixed steam from the vacuum container.
The Soventdampferzeuger may have at least two along the flow channel spaced from each other steam generator stages, with the first of the two steam generator stages is in a first portion of the Flow channels, a first Soldenssattdampfstrahl is generated, and the two steam generator stages can be designed and arranged such that at the production of the second Soladssattdampfstrahls the following listed flows have the same flow direction:

1. (a) the first solvent steam jet,
2. (b) mixed steam sucked through the first suction opening,
3. (c) mixed vapor sucked through a second suction port and
4. (D) the second Soldenssattdampfstrahl.

The solvent steam generator can have a pipe guided centrally in the flow channel for feeding the steam generator stages with superheated solvent, which pipe can be flexible at least in sections.

The direction of a steam jet which can be guided out of the outlet opening of the flow channel can be variable as a function of the position of the solid insulation.

The vacuum container may also consist of an active part receiving the transformer housing and an evaporator housing, which is attached to a housing opening to the transformer housing and which receives the solvent evaporator and a separator for separating non-evaporated solvent and any existing insulating oil between the outlet opening and the opening of the Transformer housing and to remove the deposited solvent and any existing insulating oil is provided from the vacuum housing.

The evaporator housing may comprise two chambers separated from one another by a partition wall, a first of which receives the solvent steam generator and mixed steam from the transformer housing, and the second chamber has an outlet leading to the transformer housing for guiding a steam flow following the removal of the separated solvent the optionally existing insulating oil contains mainly Solventsattdampf and mixed steam.

The separating device may have at least one flow circulation plate for deflecting a steam jet which can be guided through the outlet opening of the flow channel from the first into the second chamber, at least one flow plate for collecting the separated, unevaporated solvent and the optional insulating oil, and also at least one evacuation pipe for collecting and removing the separated solvent and the optional insulating oil from the vacuum vessel.

The vacuum container can receive a discharge line guided at its lowest point, which is connected to an evacuatable emptying container by an opening of the vacuum container, preferably designed as a discharge nozzle.

When carrying out the process, at least water and solvent are separated from a mixed steam stream which forms during heating, and after completion of the first phase of the heating process, the heated active part is kept at reduced pressure for drying. During this negative pressure phase, the oil / solvent mixture present at the bottom of the housing is withdrawn via the discharge nozzle by a pump and, on the other hand, aspirated in parallel via a small drainage pipe located inside the drainage nozzle into a drainage container which is at a lower pressure than the transformer housing. During this negative pressure phase, the pumped and extracted oil / solvent mixture is reheated and fed to the housing until all the solvent has evaporated and is condensed in a condensation system located outside the housing. The oil accumulated at the bottom of the housing is emptied into the drainage container via a drainage nozzle and pump on the one hand and via a small drainage pipe on the other hand. If, during the vacuum phase, the level of the oil / solvent mixture in the transformer below the discharge nozzle drops, so that circulating and heating by the feed pump is not possible, the present at the bottom of the transformer housing oil / solvent mixture via small discharge line to the discharge tank and the distillation evaporator, circulated, circulated and heated until all of the solvent has evaporated, condensed in a condensation system external to the housing. The oil in the distillation evaporator is fed to the used oil tank.

If the temperature of the transformer active part has not yet reached the specified values, new solvent is introduced into the transformer housing and further heating and vacuum phases are initiated in the same manner as the first heating phase. The main part of the waste oil from the active part is washed out in the first heating phase. The emptying of small residual amounts of oil / solvent mixture in the subsequent heating phases is carried out through a small discharge line in the drain tank and via feed pump, solvent heater in the distillation evaporator and after evaporation of residual solvent and condensation in a lying outside the housing condensation system, the oil is fed to the waste oil tank , This ensures that in the subsequent drying phase, the waste oil washed out of the solid insulation is largely removed and thus no longer pollutes the transformer.

In the subsequent drying phase (fine vacuum phase), the supply of Solventsattdampf is interrupted and sucked at a reduced compared to the heating phase vacuum, mixed steam from the transformer housing.

Alternatively, during the fine vacuum phase, a superheated solvent vapor serving for reheating the solid insulation is introduced into the transformer housing. During the reheating, the temperature of the superheated solvent vapor introduced is kept higher than the temperature of the solid insulation and the pressure in the vacuum container is kept lower than the pressure which the solvent vapor has at its condensation point determined by the temperature of the solid insulation.

As a result, the solid insulation of the active part, which cools down when it is kept under reduced pressure, is reheated by the introduction of superheated solvent vapor. Since the pressure of the introduced, superheated solvent vapor always below its by the temperature of the solid insulation respectively. the condensing point certain condensing pressure, transfers the superheated solvent vapor energy only by convection and radiation, so that condensation on the surfaces of the solid insulation is avoided. The superheated solvent vapor flows into all channels and cavities of the solid insulation due to the pressure difference and preferably warms them by convection. As a result of the fact that no superheated solvent vapor condenses on the active part and penetrates into the insulation, no solvent has to be re-evaporated, as a result of which no temperature reduction results due to re-evaporation of solvent, which saves energy, increases the drying quality as a result of the higher insulation temperature and reduces the drying time.

Accordingly, not only the throughput time, but also the energy consumption of the inventive drying process compared to the prior art, in which such reheating with superheated solvent vapor in combination with injection of superheated solvent / oil mixture is not provided in several stages.

The device provided for carrying out the method according to the invention can communicate, in addition to the active part accommodating transformer housing communicating a vacuum system, a device for heating solvent, arranged within the transformer housing at least 2 stages Solventsattdampf and superheated Solventdampf generating apparatus, a condensation device for sucking the mixed steam from the transformer housing contain. This Solventsattdampf forming at least two-stage device has a arranged below the transformer housing emptying tank for emptying residual heated solvent / oil mixture, from the transformer housing, a arranged outside the discharge container, connecting vacuum control valve for regulating the pressure in function of the pressure prevailing in the transformer housing. Attached to the discharge socket of the transformer housing is a connection flange with drain line and integrated, adjustable height drain line.

The steam generator may include at least two jet injector ducts having the contour of venturi nozzles and at least two supply pipes arranged in the jet injection ducts, connecting pipes having injection ports for supplying superheated solbent / oil mixture during heating, and supplying heated solvent from the solvent supply tank for the reheating.

The injection openings of solvent can be arranged in the region of the bottleneck of the jet injection channels determined by the contour of the venturi tube.

In the case of multistage solvent steam generators, it is possible for the individual solvent steam generators to have intake openings for mixed steam from the transformer housing. As a result, the Solventdampfumwälzmenge is advantageously increased and the regulation of the solvent temperature optimized.

In the case of multistage solvent steam generators, the injection channels and the outlet openings may be spatially variable in the case of the individual solvent steam generators.

The jet injection channels may be oriented such that flows of saturated saturated steam and or superheated solvent vapor in variable directions emerging from the last channel during heating pass into a space bounded by the active part and the inner wall of the transformer housing.

Alternatively, the at least 2 stage Solventsattdampf and superheated Solventdampferzeugende apparatus can be installed in a connected to the transformer housing evaporator housing. The supply of heated solvent / oil mixture in the evaporator housing via feed nozzle and Solventzuführrohr to at least 2 stages Solventsattdampf and superheated Solventdampf generating apparatus. Partitions and drain sockets in the evaporator housing ensure that the non-evaporated solvent / oil mixture is fed directly to a feed pump and does not flow into the transformer housing. As a result, only the solvent condensed on the active part has to be removed through the extremely small drainage nozzle on the transformer housing. Therefore, the capacity of the solvent pump can be increased even with a small discharge nozzle of the transformer housing in an advantageous manner, which ensures a large Verdampferheizleistung and reduces the drying time.

The drying device may include a downstream of the solvent heater device for distilling off residual solvent with an outside of the device arranged, connecting vacuum control valve for controlling the pressure. This ensures a distillation even of small amounts of a solvent / oil mixture outside the transformer housing.

This distillation takes place parallel to the drying, thereby on the one hand drying time is shortened and on the other hand ensures that no waste oil remains in the transformer housing.

A temperature sensor for measuring the temperature of the solid insulation can be arranged on a part of the solid insulation designed as a barrier insulation.

Outside the transformer housing, a control valve connecting the transformer housing with the condensation device may be provided for regulating the pressure prevailing in the transformer housing in function of the temperature of the solid insulation during the reheating.

Air heated in the air-cooled condenser / separator may be routed to a bottom wall of the transformer housing. The heat radiation of the housing can be reduced and energy saved accordingly.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1

eine erste Ausführungsform einer Trocknungsvorrichtung, in der das erfindungsgemässe Verfahren zur Trocknung und Reinigung der Imprägnieroel enthaltenden Feststoffisolationen eines elektrischen Gerätes durchgeführt wird,

Fig.2

in vergrösserter Darstellung eine detaillierte Darstellung eines Solventsattdampferzeugers der Trocknungsvorrichtung gemäss Fig.1,

Fig.3

eine gegenüber der erste Ausführungsform ergänzte zweite Ausführungsform der Trocknungsvorrichtung,

Fig.4

in vergrösserter Darstellung eine detaillierte Darstellung eines Solventsattdampferzeugers der Trocknungsvorrichtung gemäss Fig.3,

Fig.5

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

Fig.6

ein Diagramm, in dem der Verlauf wesentlicher Verfahrensparameter des erfindungsgemässen Verfahrens, wie der Druck im Gehäuse des elektrischen Gerätes, die Temperatur der Feststoffisolation und das Solvent/Ölniveau im Gehäuse, während der verschiedenen Prozessphasen mit zusätzlicher Nachheizphase 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 device, in which the inventive method for drying and cleaning impregnating oil-containing solid insulation of an electrical device is performed,

Fig.2

in an enlarged view a detailed representation of a Solventsattdampferzeugers the drying device according to Fig.1 .

Figure 3

a comparison with the first embodiment, the second embodiment of the drying device,

Figure 4

in an enlarged view a detailed representation of a Solventsattdampferzeugers the drying device according to Figure 3 .

Figure 5

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, the temperature of the solid insulation and the solvent / oil level in the housing, during the various stages of the process are shown, and

Figure 6

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, the temperature of the solid insulation and the solvent / oil level in the housing, during the various process phases are shown with additional Nachheizphase.

WAYS FOR CARRYING OUT THE INVENTION

In all figures, like reference numerals designate like-acting parts. The in the FIGS. 1 and 2 drying device shown is used to dry a solid 1.5 containing active part 1.1, and the removal of the impregnating oil from active part 1.1 and solid insulation 1.5 of a designed as a transformer electrical device in the vacuum-tight running housing first

To heat the active part 1.1 can be heated in a heater 2 either solvent or solvent / oil mixture. The solvent is generally a light oil having a substantially higher boiling point than water and a substantially lower boiling point than an impregnating oil which may still be present in the solid insulation 1.5 during drying and which will fill the housing 1 of the transformer during its operation, prior to drying of the active part 1.1 is emptied from the transformer housing 1. The necessary for the heating of the active part 1.1 solvent is fed from a Solventlagertank 13.2 via shut-off valves 21,21.7, drain line 6, emptying port 1.4 and alternatively parallel via shut-off valve 21.6, 21.4, drain line 7 in the vacuum housing 1 until level switch 5 is flooded.

In the heating phase H1, the solvent present in the housing 1 through the drain port 1.4, drain line 6, shut-off valve 21.7, drain line 7, Shut-off valves 21.4,21.6, filter 8, shut-off valve 21.1, the feed pump 9 is supplied and then, via shut-off valve 21.2, Solventzuführleitung 2.3 promoted to the solvent heater 2. The superheated solvent is fed via Solventverteilleitung 2.2, shut-off valve 22 through a Abdeckflansch 1.3 to a arranged inside the transformer housing 1 Solventzuführrohr 3.4, flexible connecting pipe 3.5, to the injection ports 1.step 3.1.1. When flowing overheated solvent or solvent / oil mixture in the stage 1 jet injection channel 3, solvent evaporates partially with simultaneous cooling. The injection openings 1st stage 3.1.1 and the stage 1 jet injection channel 3 therefore act more or less as evaporators. By the flow of superheated solvent or solvent / oil mixture in the running in the manner of a venturi stage 1 jet injection channel 3 at high speed and the simultaneous emergence of Soladssattdampf 3.9 in Stage 1 jet injection channel 3 is additionally mixed solvent vapor 3.10 from the housing 1 in the stage 1 Jet Injection channel 3 is sucked in, which advantageously leads to higher turbulence of the solvent vapor in the housing 1. The stage 1 jet injection channel 3 is directed so that the solvent vapor stream 3.9 emerging from this channel and possibly also containing solvent and waste oil and the solvent mixed vapor 3.10 drawn in through the inlet opening 1.step 3.1 flows into the stage 2 jet injection channel 3.2.

The remaining heated solvent or solvent / oil mixture is supplied through connecting tube 3.7, flexible connecting pipe 3.5 to the injection openings 2nd stage 3.2.2, which are also at the narrowest point of the stage 2 jet injection channel 3.2. Upon exiting the heated solvent or solvent / oil mixture in the stage 2 jet injection channel 3.2, the heated solvent or solvent / oil mixture cools down further with the simultaneous emergence of Soladssattdampfströmung 3.9 high speed in stage 2 injection channel 3.2. As a result, as described in stage 1, solvent mixed steam 3.10 is sucked out of the housing 1 through the suction opening 2. stage 3.2.1 into the stage 2 jet injection channel 3.2. which, in an advantageous manner, further increases turbulence of the solvent vapor in the housing 1. In this case, the stage 2 jet injection channel 3.2 is directed so that the emerging from the injection openings 2nd stage 3.2.1 and optionally still containing solvent and waste oil Solvent vapor flow 3.9 and sucked through the suction 2.Stufe 3.2.1 Solventmischdampf 3.10 the stage 3 jet injection channel 3.3 flows. This advantageously increases the turbulence of the solvent vapor in the housing 1.

The remaining heated solvent or solvent / oil mixture is fed through connection tube 3.7, flexible connecting tube 3.5 to the injection openings 3.stage 3.3.2, which are also at the narrowest point of the stage 3 jet injection channel 3.3. Upon exiting the heated solvent or solvent / oil mixture in the stage 3 jet injection channel 3.3, the heated solvent or solvent / oil mixture cools down further with the simultaneous emergence of Soladssattdampftströmung 3.9, high speed in stage 3 jet injection channel 3.3. As a result, as described in stage 1 and stage 2, solvent mixed steam 3.10 is sucked out of the housing 1 through the suction opening 3. stage 3.3.1 into the stage 3 jet injection channel 3.3. which advantageously increases turbulence of the solvent vapor in the housing 1 again. In this case, the stage 3 jet injection channel 3.3 are directed so that the emerging from the injection openings 3.Stufe 3.3.2 and optionally still solvent and waste oil contained solvent vapor flow 3.9 and sucked through the suction 3.Stufe 3.3.1 Solventmischdampf 3.10, the exiting Solventsattdampf / mixed steam flow 3.11 forms and at high speed from the outlet opening Solventmischdampf 3.8, in the free space between transformer housing 1 and active part 1.1 exits. This optimizes advantageously turbulence and speed of the solvent vapor in the housing 1, the temperature control solvent mixed steam 3.11, and the drying quality with simultaneous reduction of the heating time.

The transformer housing 1 has at the bottom in its bottom a drain port 1.4 for condensed solvent, as well as for optionally washed out of the solvent from the solid insulation 1.5 waste oil. The emptying nozzle 1.4 is connected via a drain line 7, shut-off valves 21.4, 21.5, filter 8.1, a drain tank 10, check valve 21.11 with a feed pump 9.1. Discharge container 10 is connected via vacuum control valve 11, vacuum connection line 17.1, shut-off valve 24.1 with the vacuum system 19 and alternatively via vacuum control valve 11, vacuum connection line 17.1, shut-off valve 24, with the N2 gas storage 20, for minimal pressure increase in the emptying container 10 during solvent / oil emptying. The outlet of the feed pump 9.1 is connected via a shut-off 21.13 with the Solventerhitzer 2 or alternatively via a check valve 21.12 with waste oil tank 13, for receiving the possibly existing waste oil, which dissolved out during drying of the transformer active 1.1 by the solvent from the solid 1.5 and subsequently by distillation of Solvent was separated. Emptying nozzle 1.4 is connected in parallel via drain line 6, shut-off valve 21.7, filter 8, shut-off valve 21.1 with the feed pump 9. The outlet of the feed pump 9 is connected via a shut-off valve 21.2 with the Solventerhitzer 2 or alternatively via a shut-off valve 23, with Altöltank13, for receiving distilled Altoel, or alternatively via shut-off valve 21.16,21.17, with Solventlagertank 13.2 for recycling of any solvent from the transformer housing.

The Solventerhitzer 2 is connected via Solventverteilleitung 2.2, shut-off valve 21.3 with distillation evaporator 12. The distillation evaporator 12 is connected via vacuum control valve 11.1, vacuum connection line 17.1, shut-off valve 24.1 with the vacuum system 19. Emptying of distilled Altoel via shut-off valve 21.10, feed pump 9.1, shut-off valve 21.12 in the waste oil tank 13 or alternatively, via shut-off valve 21.14, filter 8, shut-off valve 21.1, feed pump 9, shut-off valves 21.2 and 23 in the waste oil tank.

The transformer housing 1 is connected via a first mixing steam leading line 14.1, a Solventdampfregelventil 14, an air-cooled condenser / separator 16 and a mixed steam condenser 17 with a vacuum system 19. The mixed steam condenser 17 has two outlets, one of which, connected to the vacuum system 19 and the other for emptying of solvent and water, via shut-off valve 21.15, in a, a water outlet valve 18.2, containing separation container 18th

The air-cooled condenser / separator 16 has a connecting piece which serves to supply air to a fan 16.1 and a further connecting piece, through which the heated air is guided via a hot air line 16.2 to the bottom of the transformer housing1. Eventually condensed Solvent / oil vapor is fed via outlet pipe 16.4, solvent / oil Abtropfleitung 16.5, shut-off valve 21.8, filter 8, 21.1 Absperventil the feed pump.

At the Figure 3 and 4 apparent second embodiment of the drying device is a 2-stage solvent steam generating device consisting mainly of stage 1 jet injection channel 3, stage 2 jet injection channel 3.2, and injection port 1st stage 3.1.1, injection port 2nd stage 3.2.2, in one with the Transformatorgehäuse1 in Connection standing evaporation housing 4 installed. The evaporation housing 4 has a connection flange for connection to transformer housing 1, a feed connection 4.4, which is connected via Solventabsperrventil 21.17, Solventverteilleitung 2.2 with the Solventerhitzer 2. Furthermore, a drain pipe 4.3, in which the non-evaporated solvent or Solventoelgemisch 4.11 via Solventabsperrventil 21.18, Solventverteilleitung 4.12, filter 8, Solventabsperrventil 21.1 the feed pump 9 is supplied.

In the heating phase H1, the solvent overheated in the solvent heater 2 via Solventverteilleitung 2.2, shut-off valve 21.17, feed 4.4 solvent supply 3.4, led to the injection ports 1.step 3.1.1. When flowing in superheated solvent or solvent / oil mixture in the stage 1 jet injection channel 3, solvent evaporates partially with simultaneous cooling. The injection openings 1st stage 3.1.1 and the stage 1 jet injection channel 3 therefore act more or less as evaporators. By the flow of superheated solvent or solvent / oil mixture in the running in the manner of a venturi stage 1 jet injection channel 3 high speed and simultaneous formation of Soladssattdampf 3.9, in Stage 1 jet injection channel 3 is additionally mixed solvent vapor 3.10, through a feed pipe 4.10, from the housing 1 sucked into the, stage 1 injection channel 3, which advantageously leads to higher turbulence of the solvent vapor in the evaporation housing 4 and in the housing 1. In this case, the stage 1 jet injection channel 3 is directed so that a part of the flow channel 3 exiting and optionally still solvent and waste oil contained Solventdampfströmung 3.9 exits on the one hand in the free space in the evaporation housing 4 and on the other hand, a portion of Solventsattdampfströmung 3.9 the stage 2 jet injection channel 3.2 flows.

The remaining heated solvent or solvent / oil mixture is fed through connecting tube 3.7, the injection ports 2nd stage 3.2.2, which are also at the narrowest point of the stage 2 jet injection channel 3.2. At the exit of the heated solvent or solvent / oil mixture in the stage 2 jet injection channel 3.2, the heated solvent or solvent / oil mixture cools down further with the simultaneous emergence of a Solventsattdampfströmung 3.9, high speed in stage 2 jet injection channel 3.2. As a result, as described in stage 1, solvent mixed steam 3.10 is sucked out of the housing 1 into the stage 2 jet injection channel 3.2 by a feed pipe 4.10, which advantageously results in higher turbulence of the solvent vapor in the evaporation housing 4 and in the housing 1 and the heating time reduced. In this case, the stage 2 jet injection channel 3.2 is directed so that the emerging and possibly still solvent and waste oil contained Solventdampfströmung 3.9 in the flow circulation plate 4.5 changes the direction and solvent / oil mixture 4.11 flows along the flow circulation plate 4.5 and then against the Solventdampfströmung to the connection flange of the evaporation housing drips off and drains through outlet 4.3. The direction of the Soladssattdampfs / mixed steam 3.11 is changed again at the top of the partition 4.6. The steam is guided to the straightening plate 4.5 and then flows at high speed and turbulence in the transformer housing 1. Any Solvent / Oelgemisch 4.11 still present in the Solventmischdampfströmung 3.11 is collected in the drain plate 4.7 and supplied via drain pipe 4.8 the drain pipe 4.3.

• Zunächst werden mit der Vakuumanlage 19 bei geöffnetem Solventdampfregelventil 14 und geöffnetem Absperrventil 24.2 das Transformatorgehäuse 1, der luftgekühlte Kondensator/Abscheider 16, der Mischdampfkondensator 17 und der Trennbehälter 18 evakuiert. Zugleich wird vom Solventlagertank 13.2 eine genügende Menge Solvent über das Solventabsperrventil 21, 21.7, Ablassleitung 6,Entleerungsstutzen 1.4 mittels Druckdifferenz in das Transformatorgehäuse 1 eingesaugt und mit dem Niveauschalter 5 überwacht.

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 16, the mixed steam condenser 17 and the separation vessel 18 are evacuated with the vacuum system 19 with the solvent vapor control valve 14 open and the shut-off valve 24.2 open. At the same time a sufficient amount of solvent on the Solventabsperrventil 21, 21.7, drain line 6, emptying port 1.4 is sucked by means of pressure difference in the transformer housing 1 and monitored with the level switch 5 from the Solventlagertank 13.2.

In a now following off Figure 5 apparent heating phase H1, the solvent present in the transformer housing 1 on the one hand via drain port 1.4, drain line 6, Solventabsperrventile 21.7,21.1, Filter 8, with the feed pump 9, via solvent supply line 2.3 fed to the Solventerhitzer 2, heated to a temperature slightly below the ignition temperature of Solvent and via Solventverteilleitung 2.2, shut-off valve 22 through the Abdeckflansch 1.3 to the arranged within the transformer housing 1 multi-stage jet injection channels 3, 3.2.3.3 and pumped through the multi-stage injection ports 3.1.1, 3.2.2, 3.3.2 in the jet injection channels. 3 , 3.2, 3.3 sprayed. On the other hand, the solvent present at the bottom of the transformer housing 1 is additionally sucked through discharge line 7, Solventabsperrventile 21.4, 21.5, Filter 8.1, in the standing at a lower pressure drain tank 10. The pressure is controlled by vacuum control valve 11, vacuum sensor 10.2 and vacuum system 19. The feed pump 9.1 sucks the solvent present in the Entlerungsbehälter 10 via the shut-off valve 21.11 and delivers it continuously via the shut-off valve 21.13, the Solventerhitzer 2 and the shut-off valve 22 in the Solventdampferzeuger.

On the superheated solvent acts a pressure which is much higher than the pressure prevailing in the transformer housing 1. When the solvent exits in stages from the injection openings 3.1.1, 3.2.2, 3.3.2, the pressure in the solvent drops sharply, it evaporates due to the high solvent temperature, a large part of the heated solvent in several stages with simultaneous cooling by the amount of his heat of vaporization. As a result of lower pressure in the jet injection channels 3, 3.2, 3.2 relative to the transformer housing 1, due to the action of solvent mixed steam 3.10 flows in several stages in the jet injection channels 3, 3.2, 3.3, mixed with further cooling with the Solventsattdampf 3.9. The temperature is monitored by temperature controllers 2.1 and 3.12.

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 with the vacuum system 19 aspirated via Solventdampfregelventil 14, any oil vapor and oil drops are deposited in the air-cooled condenser / separator 16, and condensed a part of solvent vapor and fed via Solventabsperrventil 21.8, 21.1, filter 8, the feed pump 9. The remaining solvent and water vapor condenses in the mixed steam condenser 17. The condensate flows via Solventabsperrventil 21.5 to the separation tank 18. The separated solvent is returned to the solvent circuit with the feed pump 9.2 via check valve 25, shut-off valve 21.16 and heated in the solvent / oil heater 2. The separated water is drained via the water drain valve 18.2.

In the transformer housing 1 resulting and possibly waste oil-containing solvent condensate is also via drain opening 1.4, drain line 6, shut-off 21.7,21.1, filter 8, funded with the pump 9 to the solvent / Öhlitzer 2 and again for evaporation the jet injection channels 3, 3.2, 3.3 respectively supplied to the Solventeinspritzöffnungen 3.1.1, 3.2.2, 3.3.2. In addition, the present at the bottom of the transformer housing 1 solvent / oil mixture is sucked through drain line 7, Solventabsperrventil 21.4, 21.5, Filter 8.1, in the standing at a lower pressure drain tank 10 and supplied with feed pump 9.1 via open Solventabsperrventil 21.13 back to the heating circuit.

If the level of the solvent 5.1 in the transformer housing 1 drops too low, additional solvent is sucked in via the solvent shut-off valve 21 from the solvent reservoir 13.2 until the level indicator 5 is flooded again.

The solvent is injected through the injection openings 3.1.1, 3.2.2, 3.3.2 with advantage at the narrowest point in the jet injection channels 3, 3.2, 3.3. This results in a particularly high flow velocity and a correspondingly high negative pressure. This leads to a jet effect, wherein the existing in the transformer housing 1 Solventmischdampf 3.10, is sucked into the jet injection channels 3, 3.2, 3.3. The drawn-in mixed steam mixes with the superheated solvent injected at high speed and the solvent saturated steam 3.9 formed on injection. This produces the advantageous effect that by stepwise sucking of mixed steam into the series-connected jet injection channels 3, 3.2, 3.3 ,, a fast and accurate Temperature control of the flowing into the transformer housing 1 Soladssattdampfes 3.11 is achieved, and he flows at an increased speed present in the transformer housing 1 active part 1.1 turbulent flows and heats quickly and uniformly.

The arrangement of the at least two jet injection channels 3, 3.2 in such a way that the exiting Solventsattdampf flows into the existing free space between the active part 1.1 and the inner wall of the transformer housing 1, a high-velocity solvent vapor flows within the transformer housing 1, which the active part 1.1 everywhere flows around with turbulent, Solventdampfströmung, whereby a uniform heating of the active part 1.1 is significantly accelerated.

In addition, as a result of the high solvent temperature and the multistage evaporation with simultaneous cooling, a large part of the superheated solvent evaporates, which advantageously leads to the fact that only a small part of the non-evaporated but cooled solvent has to be removed from the bottom of the transformer housing 1.

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 4.2, the periodic Solventzuführung is interrupted, that is, the Solventabsperrventil 21 closed and off Figure 5 apparent phase D1 introduced in which the solvent / oil mixture is circulated as described above, with continuous mixed solvent vapor 3.11 is taken. Since the oil content in the injection channels 3, 3.2, 3.3, does not evaporate, with continuous removal of mixed steam from the transformer housing 1 and condensation of the withdrawn solvent mixed steam 3.11 in the air-cooled condenser / separator 16 and the mixed steam condenser 17, the waste oil content in the transformer housing 1 steadily increases , until practically only pure waste oil is present. This oil is now emptied on the one hand with the feed pump 9, via drain line 6, Solventabsperrventile 21.7, 21.1, 21.2, Oelabsperrventil 23 during the phase D1 in the oil tank 13. The largely complete oil emptying of the transformer housing 1 takes place On the other hand, through drain line 7, Solventabsperrventile 21.4, 21.5, filter 8.1 in the standing under a deeper pressure drain tank 10. In the transformer housing 1 via vacuum / pressure control valve 11.2, by N2 or dry air, a slightly higher pressure than in the drain tank 10 constructed. The oil in the emptying container 10, is emptied with feed pump 9.1 via Solventabsperrventile 21.12 in the waste oil tank 13. The advantageously ensures that substantially all Altoel is removed from the transformer housing 1 and no longer pollutes the transformer.

After that, in one Figure 5 apparent phase F, from Solventlagertank 13.2 a sufficient amount of solvent via the Solventabsperrventil 21, 21.7, drain line 6, emptying nozzle 1.4 by means of pressure difference in the transformer housing 1 sucked by level switch 5 monitored.

After that, in one Figure 5 apparent phase H2, heated solvent with feed pumps 9, 9.1, via the Solventerhitzer 2, Solventabsperrventil 22, the injection openings 3.1.1, 3.2.2, 3.3.2, supplied and circulated in the aforementioned manner and in the jet injection channels 3, 3.2 , 3.3 evaporated.

Once the solid insulation 4.2 are heated to a temperature sufficient for drying resp. to wash out any existing waste oil, can again a in Figure 5 Phase D2 be introduced, while as described in phase D1 by circulating the solvent / oil mixture and evaporation of the solvent vapor, the solvent content in the solvent / oil mixture is continuously reduced until the level switch 5.1 falls below and therefore no circulation through pump 9 is more possible. Thereafter, the remaining in the transformer housing 1 solvent / oil mixture as described in phase D1 in the discharge tank 10, emptied and with feed pump 9.1 via Solventabsperrventile 21.13, Solventerhitzer 2, Solventabsperrventile 21.3, within the heated (12.1) distillation evaporator 12, arranged Verteilschirmes 12.2, supplied until the permissible level 12.4 is reached. Resulting solvent vapor is pressure-controlled with vacuum pressure switch 12.3, via vacuum pressure control valve 11.1, shut-off valve 24.1, condensed in the mixed steam condenser 17, emptied into separation tank 18 and any existing air through Vacuum system 19 sucked off. With closed Solventabsperrventi 21.11 and Solventabsperrventil open 21.13, with the pump 9.1, the solvent / oil mixture via Solventerhitzer 2, distillation evaporator 12, as long circulated until only Altoel is present. The oil emptying of the distillation evaporator 12 takes place with feed pump 9.1 via Solventabsperrventile 21.12 in waste oil tank 13th

If at the end of the pressure reduction phase D2, the temperature of the solid insulation 4.2 as a result of evaporation of water and solvent from solid insulation 4.2 and active part 1.1 drops too much, or if in the heating phase H2 much Altoel is washed out of the solid insulation 4.2, can in a Figure 5 apparent phase F new solvent as described previously be fed into the transformer housing. Thereafter, in phase H3 heated solvent with feed pumps 9, 9.1 via the Solventerhitzer 2, Solventabsperrventil 22, the injection openings 3.1.1, 3.2.2, 3.3.2 supplied and circulated in the aforementioned manner and evaporated in the injection channels 3, 3.2, 3.3 become.

Once the solid insulation 4.2 are heated again to a temperature sufficient for drying, again in Figure 5 phase D3 are introduced, while as described in phase D2 by circulating the solvent / oil mixture and evaporation of the solvent vapor of the solvent content in the solvent / oil mixture continuously reduced until the level switch 5.1 is reached. Since only a small amount of waste oil from the solid insulation 1.5 is to dissolve, the level of the solvent / oil mixture in the transformer housing 1 is already dropped after a short circulation time and simultaneous evaporation of the solvent at a relatively high pressure in the transformer housing 1 to the level switch 5.1. The emptying of the solvent / oil mixture in the transformer housing 1 in the discharge tank 10, the distillation and the waste oil discharge takes place as described in phase D2, but without pressure build-up in the transformer housing 1 via N2 / air storage.

In one Figure 5 apparent, by switching off the feed pump 8 introduced phase V is present in the transformer housing 1 mixed steam the air-cooled condenser / separator 16 and the Mixed steam condenser 17 fed. Eventually entrained oil vapors are deposited in the air-cooled condenser / separator 16. By means of condensation of solvent and water vapor in the mixed steam condenser 17, the pressure in the transformer housing 1 is lowered to such low levels that only a small amount of moisture and solvent are present in the solid-state insulation 1.5.

In the out Figure 6 apparent process flow to cool during the fine vacuum phase V1, the solid insulation 1.5, monitored with temperature controller 4.2 due to the evaporation of moisture and solvent so far from that further evaporation due to low temperature of the insulation is greatly reduced. Since this temperature reduction of the solid insulation 1.5 can not be reversed by the heat radiation of the active part 1.1, now the transformer housing 1 during a off Figure 6 apparent phases F1 and H4 acted upon with superheated solvent vapor 11.2 as follows.

In the phase F1, the solvent is drawn from the solvent storage tank 13.2 via the solvent shut-off valve 21, 21.6, 21.5, filter 8.1 into the evacuation container 10, which is under vacuum, and the quantity is monitored with level monitoring 10.1. With the Solventabsperrventil 21.11 open the feed pump 9.1, then, via Solventabsperrventil 21.13, Solventzuführleitung 2.3 promoted to the Solventerhitzer 2, heated and via Solventverteilleitung 2.2, Solventabsperrventil 22, Abdeckflansch 1.3, feed 3.4 to the injection openings 3.1.1, 3.2.2, 3.3.2 , and injected into the jet injection channels 3, 3.2, 3.3, with formation of superheated solvent vapor. Non-evaporated solvent flows from the bottom of the transformer housing 1, via drain line 7, Solventabsperrventile 21.4, 21.5, filter 8.1, the discharge tank 10 and again the Solventheizkreilauf. On the one hand, the temperature of the superheated Solventdampfaustritts with temperature controller 4.2 is controlled so that it is above the temperature of the solid insulation 1.5. On the other hand, the pressure in the transformer housing 1 with solvent vapor control valve 14 and vacuum sensor / regulator 15, 15.1 controlled so that the pressure is always below the condensation pressure of the solvent, thereby ensuring that always superheated solvent vapor is present and therefore no solvent vapor condenses on the solid insulation 1.5. This ensures advantageously a Reheating of the solid insulation 1.5 by convection. Since no condensation of solvent vapor occurs, no solvent from the solid insulation 1.5 must be re-evaporated, which shortens the vacuum time.

Once in the transformer housing 1, the maximum allowable pressure, monitored with pressure sensor 15, is reached, it is held constant for a defined time (phase H4), that is, as long as the insulation temperature, measured with a temperature controller 4.2, still increases. This ensures that the solid insulation 1.5 is reheated during phase H4 and the drying times are shortened.

At the end of phase H4, any solvent present at the bottom of the transformer housing 1 as described above is sucked into the drainage container 10 and then returned to the solvent storage tank 13.2 via pump 9.1, via solenoid shut-off valves 21.13, 21.16, 21.17.

The phases F1, H4 can be repeated several times if necessary.

LIST OF REFERENCE NUMBERS

1

Housing, transformer housing

1.1

active part

1.2

housing openings

1.3

covering flange

1.4

drain connection

1.5

Solid insulation

2

Solventerhitzer

2.1

Temperature controller Solvent

2.2

Solventverteilleitung

2.3

Solventzuführleitung

3

Stage1 Jet Injector / Venturi

3.2

Stage2 Jet Injector / Venturi

3.3

Stage3 Jet Injector / Venturi

3.1

Intake opening 1st stage

3.2.1

Intake opening 2nd stage

3.3.1

Intake opening 3rd stage

3.1.1

Injections 1st stage

3.2.2

Injection openings 2nd stage

3.3.2

Injection openings 3rd stage

3.4

Solventzuführrohr

3.5

Flexible connecting pipe, flexible pipe section

3.6

Swivel / Swivel mount

3.7

connecting pipe

3.8

Outlet opening Solventmischdampf

3.9

Solvent saturated steam / superheated solvent vapor

3.10

Solvent mixed vapor

3.11

Solvent saturated steam / mixing steam

3.12

Temperature controller Solventsattdampf / mixed steam

4

Evaporating housing with connection flange

4.1

Temperature controller Solventsattdampf / mixed steam

4.2

Temperature controller solid insulation

4.3

drain connection

4.4

supply pipe

4.5

Flow Umlaufblech

4.6

partition wall

4.7

flow sheet

4.8

drain pipe

4.9

Flow directing plate

4.10

supply pipe

4.11

Solvent / Oelgemisch

4.12

Solventverteilleitung

5

Level switch (top)

5.1

Level switch (below)

6

drain line

7

drain line

8; 8.1

filter

9; 9.1; 9.2

feed pumps

10

emptying containers

10.1

level monitoring

10.2

Vacuum sensor / controller

11; 11.1; 11.2

Vacuum / pressure regulating valve

12

distillation evaporator

12.1

heater

12.2

Verteilschirm

12.3

Vacuum / pressure sensor

12.4

level switch

13

Waste oil tank

13.1

waste oil management

13.2

Solvent storage tank

14

Solvent steam control valve

14.1

Mixing steam line

15; 15.1

Vacuum sensor / controller

16

air-cooled condenser / separator

16.1

fan

16.2

Hot air line

16.3

Outlet opening mixing steam

16.4

Outlet solvent condensate

16.5

Solvent / oil drip line

17

Mixing steam condenser

17.1

Vacuum connection line

18

separation vessel

18.1

Solvent drain line

18.2

Water drain valve

19

vacuum system

20

N2 / dry air storage

21-21.18

Solventabsperrventile

22

Shut off valve for superheated solvent

23

Ölabsperrventil

24-24.2

Shut-off valves

25

check valve

H1, H2, H3

Heating phase with Solventsattdampf

H4

Post-heating phase with superheated solvent vapor

D1

Pressure reduction phase Oil drainage via drainage pipe

D2; D3

Pressure reduction phase Oil drainage via drainage pipe

F

Fill solvent for heating phases Solventsattdampf

F1

Fill solvent for reheating superheated solvent vapor

V1, V2

Fine vacuum phase

V2

Fine vacuum phase after postheating phase

1

Pressure in the transformer housing

2

Temperature solid insulation

3

drain line

4

drain line

5

Solvent / Oelumwälzen / heating via drainage nozzle

6

Oil drainage via drainage pipe

7

Solvent / Oelumwälzen / heating via emptying pipe

8th

Residual oil discharge via drain line with pressure increase in transformer housing

9

Residual oil discharge via drain line without pressure increase in transformer housing

Claims (15)

1. Method for drying the solid insulation (1.5) of the active part (1.1) of an electrical device containing water, possibly also insulating oil and impurities, according to the vapour-phase method, in which in at least one heating phase (H1, H2, ...) the active part is heated by the condensation of solvent saturated vapour in negative pressure, and in at least one pressure- reducing phase (D1, D2, ...) subsequent thereto mixed vapour containing at least solvent and water vapour formed thereby is sucked out of a vacuum container (1) accommodating the active part (1.1) by condensation, wherein superheated solvent is evaporated in a flow channel, forming a solvent-saturated vapour jet (3.9), which flow channel has at least a first suction port (3.1) arranged in the vacuum container (1) and an outlet port (3.8) disposed in the vacuum container, characterized in that a first fraction of the superheated solvent is injected into a first section (3) of the flow channel, generating a first solvent-saturated vapour jet (3.9), and a remaining, second fraction of the heated solvent is injected into at least one second section (3.2) of the flow channel, generating at least one second solvent-saturated vapour jet (3.9), wherein the following listed streams have the same flow direction at the generation site (3.2.2) of the second solvent-saturated vapour jet (3.9):

   (a) the first solvent-saturated vapour jet,

   (b) mixed vapour sucked in through the first suction port (3.1),

   (c) mixed vapour (3.10) sucked in through a second suction port (3.2.1)
   and

   (d) the second solvent-saturated vapour jet.
2. Method according to Claim 1, characterized in that the superheated solvent is heated to a temperature which is above the permissible drying temperature and below the ignition point of the solvent.
3. Method according to either of Claims 1 or 2, in which the vacuum container consists a transformer housing (1) that accommodates the active part (1.1) an evaporator housing (4) which is attached to the transformer housing (1) at a housing port (1.2) and accommodates the flow channel, characterized in that unevaporated solvent and any insulating oil present is separated from a vapour jet (3.11) exiting the flow channel at the outlet port (3.8) between the outlet port (3.8) of the flow channel and the port (1.2) of the transformer housing (1) and removed from the evaporator housing (4).
4. Method according to any one of Claims 1 to 3, characterized in that the first and the second section of the flow channel are each constructed in the manner of venturi nozzles, wherein the first fraction of the superheated solvent is injected into the flow channel at a constriction of the first section and the second fraction of the superheated solvent is injected into the flow channel at a constriction of the second section.
5. Method according to any one of Claims 1 to 4, characterized in that solvent and any insulating oil that accumulates during the pressure reduction phase (D1, D2, ...) is removed from the vacuum container (1) by gravitation or differential pressure and is injected back into the flow channel after the solvent has been superheated.
6. Method according to any one of Claims 1 to 5, characterized in that any insulating oil that accumulates and still remains in the vacuum container at the end of the pressure-reduction phase (D1, D2, ...) is removed from the vacuum container by gravitation or a differential pressure between the vacuum container (1) and a drainage tank (10).
7. Method according to any one of Claims 1 to 6, characterized in that in a fine vacuum phase (F) following the pressure reduction phase the superheated solvent is injected into to the flow channel to form a superheated solvent vapour.
8. Device for carrying out the method according to any one of Claims 1 to 7, comprising a vacuum container (1) for accommodating the solid insulation (1.5) of an active part (1.1) of an electrical device containing water, possibly also insulating oil and impurities, and the following, each communicating with the vacuum container:

   a vacuum system (19),

   a device for heating solvent (2),

   a solvent vapour generator arranged inside the vacuum container, having a flow channel which has at least one first suction port (3.1) arranged in the vacuum container (1) and one outlet port (3.8) arranged in the vacuum container, and

   a condensation device (17) for sucking mixed vapour out of the vacuum container (1),

   characterized in that the solvent vapour generator has at least two vapour generator stages arranged at a distance from each other along the flow channel, that a first solvent saturated vapour jet (3.9) can be generated in a first section (3) of the flow channel with the first of the two vapour generator stages, and that the two vapour generator stages are designed and arranged in such manner that the following listed streams have the same flow direction at the generation site (3.2.2.) of the second solvent-saturated vapour jet (3.9) :

   (a) the first solvent-saturated vapour jet,

   (b) mixed vapour sucked in through the first suction port (3.1),

   (c) mixed vapour (3.10) sucked in through a second suction port (3.2.1)
   and

   (d) the second solvent-saturated vapour jet (3.9).
9. Device according to Claim 8, characterized in that the solvent vapour generator has a pipe (3.5, 3.7) which passes through the middle of the flow channel for supplying the vapour generator stages with superheated solvent.
10. Device according to Claim 9, characterized in that the connecting pipe (3.7) has flexibly constructed pipe sections (3.5).
11. Device according to one of Claims 8 to 10, characterized in that the direction of a vapour jet (3.11) which can be directed out of the outlet port (3.9) of the flow channel is variable depending on the position of the solid insulation (1.5).
12. Device according to Claim 8, characterized in that the vacuum container consists of a transformer housing (1) accommodating the the active part (1.1) and an evaporator housing (4) which is attached to the transformer housing (1) at a housing port (1.2) and which accommodates the solvent vaporiser and a separating device for separating unevaporated solvent and any insulating oil present between the outlet port (3.8) and the port (1.2) of the transformer housing (1) and for removing the separated solvents and any insulating oil present from the vacuum housing.
13. Device according to Claim 12, characterized in that the evaporator housing (4) has two individual chambers separated from each other by a partition wall (4.6), of which a first chamber accommodates the solvent vapour generator and a feed pipe (4.10) carrying mixed vapour out of the transformer housing (1), and the second chamber and the second chamber has an outlet that opens into the transformer housing (1) for guiding a vapour flow (3.11) containing mainly solvent saturated vapour and mixed vapour after the removal of the separated solvent and any insulating oil present.
14. Device according to Claim 13, characterized in that the separating device comprises at least one flow baffle plate (4.5) for passing the variable direction vapour jet (3.11) from the first chamber into the second chamber, at least one baffle plate (4.7) for collecting the separated, unevaporated solvent and any insulating oil present, and also at least one discharge pipe (4.8) for collecting and removing the separated solvent and any insulating oil present from the vacuum container.
15. Device according to any one of Claims 8 to 14, characterized in that the vacuum container (1) accommodates a drainage line (7) routed at the lowest point thereof, which line communicates with a drainage tank (10) that can be emptied via an opening preferably in the form of a drainage port (1.4).

Images