EP1528342A2 - Process for drying material and apparatus for carrying out the process - Google Patents

Abstract

The drying system has a vacuum chamber (1) which encloses the workpiece (1.1). A cascade evaporator (24) evaporates a solvent. The vapor flows downward (29) from the evaporator and heats the workpiece by condensing on it. The solvent vapor (5.4) flows downward through a guide channel (5). There is a guide sheet which guides a mixed stream of water vapor and solvent vapor (30) from the vacuum chamber and forms a venturi nozzle. A circuit external to the vacuum chamber includes a pump (8), control valves (20.8,20.9) and a solvent heater (25) and a solvent evaporator (24.2).

Description

Field of the invention

The invention is based on a process for drying good, in particular solid insulation of an electrical appliance, according to The preamble of claim 1. The invention also relates to a Apparatus for carrying out the method.

• Beladen des Autoklaven mit Gut,
• Evakuieren des beladenen Autoklaven,
• Aufheizen des beladenen Autoklaven mit kondensierendem Solventdampf und gegebenenfalls zusätzlich mit der Autoklavheizung, um den überwiegenden Teil des Wasser sowie des gegebenenfalls vorhandenen Isolieröls und der Verunreinigungen aus dem Gut zu entfernen,
• Durchführen von Zwischendrucksenkungen im Autoklaven, um während des Aufheizens ausgewaschenes Isolieröl abzudestillieren und um in besonders schneller und schonender Weise die vorgenannten Substanzen zu entfernen,
• Anlegen von Feinvakuum bei eingeschalteter Autoklavheizung an den Autoklaven, um noch vorhanden Restsubstanzen aus den Feststoffisolationen zu entfernen, und
• Belüften und Entladen des Autoklaven.

In the method, the heat of condensation of a solvent vapor generated in an evaporator is used for rapid and gentle heating of the material. The drying material generally comprises the solid insulation of an electrical device, such as a power transformer. The device or at least its active part containing the solid-state isolations are arranged in a vacuum container, for example an autoclave, held under reduced pressure. When heating from the solid insulating water leaking water is supplied in the form of a solvent and steam containing mixed steam 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. Optionally present insulating oil and / or impurities are removed by distillation from the solvent. In carrying out this so-called vapor phase method, the following process steps occur:

• Loading the autoclave with good,
• Evacuating the loaded autoclave,
• Heating the loaded autoclave with condensing solvent vapor and possibly also with the autoclave heater, in order to remove most of the water and the optionally existing insulating oil and impurities from the estate,
• Carrying out intermediate pressure reductions in the autoclave in order to distil off washed-out insulating oil during the heating and to remove the abovementioned substances in a particularly rapid and gentle manner,
• Apply fine vacuum with the autoclave heating switched on to the autoclave to remove residual substances from the solid insulation, and
• Aerating and unloading the autoclave.

State of the art

The method of the type mentioned is DE 30 14 831 A removable. An in described in this prior art, according to the vapour phase method working drying device for isolierölgetränkte insulations has a the on to be dried isolations receiving evacuable autoclave, in the a cascade evaporator is arranged. This cascade evaporator is in essentially vertically aligned and contains one of a plate and a Partition wall limited flow channel. At the plate are heating coils and Guiding plates arranged. The cascade evaporator is solvent by means of a pump fed, which in a arranged outside the autoclave preheater was heated. The preheated solvent trickles with the help of the baffles along the plate from top to bottom. Here, the solvent evaporates to the Heating coils. The forming solvent vapor flows due to chimney effect in the flow channel vertically upwards and is via a steam inlet in the Insulators containing usable space of the autoclave out.

Another drying process was in the US by the company "General Electric "and" Westinghouse "applied from about 1960. The solvent was in heated outside the autoclave solvent heater and in the introduced under vacuum autoclave and thereby evaporated, as in the book "A Guide to Transformer Maintenance "by S.D.Meyers, J.J. Kelly, P.H.Parish, p.496 (Transformer Maintenance Institute, Division, S.D.Myers, Inc. Akron Ohio, 1981) mentioned. Here, the solvent is significantly above the drying temperature heated, as the solvent evaporation heat is withdrawn and thereby cools. Accurate temperature control of the solvent vapor is difficult since various factors such as pressure and temperature in the autoclave the evaporation rate and thus also influence the solvent vapor temperature.

The aforementioned dry process is also described in US 2002/0184784 A1. In this prior art, heating fluid is left in the liquid phase heated outside a drying vessel containing vacuum vessel. following the heated heating fluid is evaporated on or in a vacuum vessel.

In the publication P.K.Gmeiner "Modern vapor drying processes and plants", February 1992, Micafil Vakuumtechnik AG, Zurich MTV / E 0293000/22 are after the Vapour phase method working solvent steam drying plants with separate, outside or inside an autoclave solvent evaporators described. All those used to carry out the described methods Devices, require a autoclave heater and in addition an evaporator a complex temperature control for controlling the solvent vapor with high To regulate accuracy.

The drying of transformers in their own housing instead of in an autoclave executed vacuum-resistant container is applied since ca.1975. This is the Solvent in a solvent evaporator outside the transformer evaporated and over large and long flexible lines in the evacuated Transformer housing brought, as in the company G.Oesch, H. Schatzl, "Solvent vapor drying of power transformers" August 1976, Micafil AG, 8048 Zurich / Switzerland (order number MNV 46/1 d).

Presentation of the invention

The present invention is based on the object, the energy consumption and to reduce the lead time of the method of the type mentioned above and at the same time provide devices which in a particularly advantageous manner to Implementation of this method are suitable.

In the inventive method, the guided in the vacuum tank and heated solvent in a formed in the manner of a venturi flow channel injected. In this case, a predominantly solvent vapor-containing and by a Constriction of the flow channel guided beam formed, which is due to Suction intense with an already existing in the vacuum container share Solvent vapor mixes. Depending on the proportion and or amount of mixed steam mixed in, as well as the amount of injected hot solvent, the temperature of the From the flow channel passing solvent vapor can be controlled very precisely. At the same time, the flow stimulated by the jet is an optimal one Circulation and turbulence of the solvent vapor in the vacuum tank ensured. As a result, the amount of energy required to heat the drying material and greatly reduces the heating time. The reduction of the heating time is above all due to the fact that strong during the entire heating phase practically constant injection of heated solvent into the flow channel one large circulation of solvent vapor and thus a high Solvent vapor velocity also towards the end of the heating phase in the Vacuum tank is maintained. Despite the low energy consumption and the short cycle time required the process over that in conventional methods necessary components addition no complex additional components.

A particularly short cycle time is achieved when the heated solvent in injected through the venturi solvent vapor stream is injected. As a result The effect of the injected solvent will be the speed and the Turbulence of the guided in the Venturi nozzle solvent vapor stream substantially elevated. This results in a high speed and good turbulence of the In the vacuum vessel circulating solvent vapor and is accordingly the Drying time greatly reduced. The increased solvent vapor velocity is due the Jetwirkung also maintained towards the end of the heating phase, which is a shorter heating time in the upper temperature range and even smaller Temperature difference across the drying object ensures, reducing the quality of the Drying is significantly improved.

Advantageously, the aforementioned is guided in the Venturi nozzle Generates solvent vapor stream in a vacuum vessel arranged in the evaporator, because then by the action of the injected solvent of the Evaporator generated solvent vapor is rapidly sucked away from the evaporator, resulting in smaller pressure loss in this evaporator and thus leads to increased efficiency.

The solvent vapor stream can also be in an outside of the vacuum vessel arranged evaporator generated and through the wall into the interior of the Vacuum container are guided. As a result of the Jetwirkung then the Solvent vapor better from a guided in the vacuum tank Solvent vapor line sucked, resulting in smaller pressure drop between external Evaporator and vacuum vessel and thus also leads to increased efficiency.

Advantageously, the heated solvent at the bottleneck of the Venturi nozzle in the Injected flow channel. At the bottleneck, this points into the flow channel injected solvent particularly high speed up. This high Speed calls for a great vacuum and thus a strong jet effect out, i. a particularly strong sucking a in the vacuum container when Heating the drying material formed mixed steam flow of solvent and Water vapor in the injected solvent.

By changing the inflow and / or outflow cross section of the Flow channel can also the mixing ratio of injected hot Solvent changed to the already flowing in the vacuum tank mixed steam become. It can thus also the temperature of passing from the flow channel Solvent vapor flow controlled at high speed and with good accuracy become.

The inventive method is characterized by a particularly high Efficiency, when in the guided inside the vacuum tank Mixed steam flow cold solvent is injected. By injecting cold Solvent, such as in a vacuum container arranged in the condensation space, is a portion of the solvent vapor present in the mixed steam by jet action sucked in and condensed. This increases the proportion of water vapor in the Condensation on and consequently has less solvent vapor in one outside the vacuum tank condenser as condensate be deposited, whereby the energy requirement of the process in addition is reduced. If the cold solvent in the flow direction in the mixed steam flow injected, so the mixed steam is strongly sucked because of the blasting effect and due to intensive mixing a high heat recuperation by heating the achieved injected cold solvent.

A further reduction of the energy requirement of erfindungemässen method is achieved in that the mixed steam flow out of the vacuum tank and condensed outside the container in two or more stages, and that with the output in a first of the stages in the condensing of mixed steam Condensation heat heating air is heated.

In a for carrying out the inventive method in simple and economically suitable device, which in addition to the vacuum tank also a solvent steam generator and a device for condensing the Having mixed steam flow, the solvent steam generator contains a inside the Vacuum container arranged and designed in the manner of a Venturi nozzle Flow channel and a guided in the flow channel device for Injecting heated solvent into the flow channel. By a particularly good mode of action, this device is characterized when the Injection device at the bottleneck of the Venturi nozzle in the flow channel empties. Include particularly expedient embodiments of the injection device an opening with injection openings in the flow channel Solventverteilkanal and / or at least one held in the interior of the flow channel injection nozzle.

Heating energy can be saved and thus the efficiency of the process on be improved if provided for heating the vacuum tank Heating device is designed as a water heater for the solvent.

A simple control of temperature and mixing ratio of the Flow channel escaping solvent vapor can be achieved in that a directional channel limiting the flow channel, changing the inflow and / or Outflow cross section of the flow channel is adjustable.

Much heating energy is saved by the fact that in the vacuum tank at least an injector for cold solvent receiving and from the mixed gas flowed through the condensation chamber of the condensation device is arranged. With Advantage is this condensation space as a flow channel for the mixed gas formed and has inflow as an inflow channel of a venturi acting sheet on and / or a drain sheet and / or downstream Baffle.

The required heating energy is additionally reduced by the fact that the Condensing device arranged outside the vacuum container, having air-cooled condenser for generating heating air.

In a further preferred embodiment of the inventive Drying device is the vacuum container as a housing of a transformer executed and in a preferably heatable with air Wärmeisolierhaus arranged.

Description of the drawing

Fig.1

eine Trocknungsvorrichtung nach der Erfindung, enthaltend einen geschnitten dargestellten, Feststoffisolationen eines Transformators als Trocknungsgut aufnehmenden Vakuumbehälter, einen Solventdampferzeuger zum Aufheizen, Zuführen und Verteilen von Solvent und zum Erzeugen von Solventdampf und einen Vorrichtung zum Kondensieren von Solventdampf,

Fig.2

eine erste Ausführungsform des in der Trocknungsvorrichtung nach Fig.1 enthaltenen Solventdampferzeugers,

Fig.3

eine zweite Ausführungsform des in der Trocknungsvorrichtung nach Fig.1 enthaltenen Solventdampferzeugers,

Fig.4

eine erste Ausführungsform der in der Trocknungsvorrichtung nach Fig.1 enthaltenen Kondensationsvorrichtung,

Fig.5

eine zweite Ausführungsform der in der Trocknungsvorrichtung nach Fig.1 enthaltenen Kondensationsvorrichtung,

Fig.6

eine abgewandelte Ausführungsform der Trocknungsvorrichtung nach Fig.1, bei der der Vakuumbehälter vom Gehäuse eines Transformators gebildet ist,

Fig.7

eine Ausführungsform des in der Trocknungsvorrichtung nach Fig.6 enthaltenen Solventdampferzeugers,

Fig.8

eine erste Ausführungsform der in der Trocknungsvorrichtung nach Fig.6 enthaltenen Kondensationsvorrichtung,

Fig.9

eine zweite Ausführungsform der in der Trocknungsvorrichtung nach Fig.6 enthaltenen Kondensationsvorrichtung,

Fig.10

eine abgewandelte Ausführungsform der Trocknungsvorrichtung nach Fig.1, bei der im Vakuumbehälter zusätzlich ein weiterer Solventverdampfer angeordnet ist, und

Fig.11

eine abgewandelte Ausführungsform der Trocknungsvorrichtung nach Fig.1, bei der dem Vakuumbehälter Solventverdampf zuführbar ist, der ausserhalb des Vakuumbehälters erzeugt werden kann.

Preferred embodiments of the invention will be described with reference to the accompanying drawings. Hereby shows:

Fig.1

a drying device according to the invention, comprising a cut-off solid insulation of a transformer as a vacuum-receiving vacuum vessel, a solvent steam generator for heating, supplying and distributing solvent and for generating solvent vapor and a device for condensing solvent vapor,

Fig.2

a first embodiment of the solvent steam generator contained in the drying apparatus according to Figure 1,

Figure 3

a second embodiment of the solvent steam generator contained in the drying apparatus according to Figure 1,

Figure 4

a first embodiment of the condensation device contained in the drying apparatus according to Figure 1,

Figure 5

a second embodiment of the condensation device contained in the drying apparatus according to Figure 1,

Figure 6

a modified embodiment of the drying device according to Figure 1, wherein the vacuum container is formed by the housing of a transformer,

Figure 7

an embodiment of the solvent steam generator contained in the drying device according to Figure 6,

Figure 8

a first embodiment of the condensation device contained in the drying device according to Figure 6,

Figure 9

a second embodiment of the condensation device contained in the drying device according to Figure 6,

Figure 10

a modified embodiment of the drying apparatus according to Figure 1, wherein in the vacuum container in addition a further solvent evaporator is arranged, and

Figure 11

a modified embodiment of the drying apparatus according to Figure 1, in which the vacuum vessel solvent evaporation can be supplied, which can be generated outside the vacuum vessel.

Ways to carry out the invention

In all figures, like reference numerals designate like-acting parts. In the The drying devices shown in the figures serve to dry good, in particular the solid insulation of one or more electrical devices as well removing any insulating oil that may be present in the insulation. The Drying device according to Fig.1 contains a vacuum-tight running container 1, which is equipped with a solid insulation containing electrical device, For example, a transformer, or - as shown - only with the Solid insulating containing active part 1.1 is loaded. The vacuum container 1 can be heated by means of heating pipes 2. The heating energy is in one Heat generator 3 on a flowing in the tubes 2 heat transfer medium for heating of the vacuum container 1 transmitted. The heating pipes 2 are of a double jacket surrounded and form together with the jacket a Solventerhitzer 4 a Solvent steam generator. In the solvent heater, cold solvent is heated. The solvent is generally a light oil with a much higher boiling point than water and a much lower boiling point than any in the Solid insulation existing insulating oil. The heated solvent is poured over an in 1 unsigned Solventverbindungsleitung in one within the Vacuum container 1 lying, optionally tubular, Solventverteilkanal 5 of Solventdampferzeugers out. The solvent distribution channel 5 can with advantage as exposed pipe with injection openings and or Injectors are formed. This will be a cost effective device reached. The Solventverteilkanal 5 has injection openings or injectors for the solvent on. In the area of the injection openings is the narrowest cross-section of a in the manner of a Venturi nozzle running flow channel 5.2, which by a suitably curved straightening plate 6, an outer wall of the Solventverteilkanals 5 and the wall of the vacuum container 1 is formed. The straightening plate 6 can through Turning and / or moving in its position can be changed. This can be done the upstream of the nozzle throat of the Venturi nozzle located inflow and the downstream of the nozzle throat located Abströmquerschnitt of Flow channel 5.2 enlarge or reduce. The vacuum container 1 has down in its bottom an opening into a drain tank 7 drain opening for condensed solvent on and optionally from the solvent from the Solid insulation washed out insulating oil. In the drain tank 7 is a Switch executed fill level indicator 7.1 arranged. The drain tank 7 is via Shut-off valve 20.1 connected to a feed pump 8. The exit of the Feed pump 8 is connected via shut-off valve 20.3 with the Solventerhitzer 4 or alternatively via shut-off valve 20.6 with a solvent storage tank 9 or via Shut-off valve 20.7 with an oil tank 19 for receiving the optionally existing insulating oil, which during drying of the material to be dried 1.1 by the Solvent removed from the solid insulations and subsequently by distillation was separated from the solvent.

Opposite the flow channel 5.2 is in the vacuum tank 1 a Condensation device arranged with a condensation chamber 10 for Heat recuperation, a baffle 10.1, baffles 10.2 and injectors 11. The condensation space 10 is down to the inside of the vacuum container. 1 open and has at its upper end a through the wall of the container. 1 guided outlet opening 10.3, which via a mixing steam line 15 and a Dampfabsperrventil 20 leads to a mixed steam condenser 16. Of the Mischdampfkondensator 16 has two outputs, one of which with a Vacuum system 18 and the other via a check valve 21 with a separation tank 17 is connected. The separation vessel 17 has two outputs, one of which on one of the removal of water serving discharge valve 22 acts and the other is connected to the input of a Solventförderpumpe 8.1 whose output optionally via a shut-off valve 20.5 to the injection nozzles 11, or over Shut-off valves 20.4 and 20.6 leads to the solvent reservoir tank 9.

The structure of two embodiments of the in the drying apparatus according to Fig.1 provided Solventdampferzeugers can be seen from Figures 2 and 3. at the embodiment of Figure 2, the Solventerhitzer 4 of Solventdampferzeugers vertically aligned heating pipes 2 on. This becomes apparent cold solvent using a feed line 4.2 at the bottom in the Solvent heater 4 out and heated there. At the upper end of the Solventerhitzer 4 is heated solvent on the above already mentioned and now with the Reference numeral 4.1 marked solvent connection line through the wall of the Vacuum container 1 in the arranged inside the container Solventverteilkanal. 5 guided. By those already mentioned above and now with the reference numeral 5.1 marked injection openings, the heated solvent as intensive Solvent flow 5.3 from the Solventverteilkanal 5 in the flow channel 5.2 emerge and there with a solvent and water vapor containing Mixed steam from the interior of the container to a predominantly solvent vapor containing steam containing 5.4. The flow channel 5.2 can over the extend entire length and / or width of a wall of the container and possibly also consist of several short sections. Is the Solventverteilkanal as exposed pipe with injection openings or injectors trained, it is through the emerging from the manifold, expanding and partially evaporating solvent, the mixed steam in the flow channel on both sides of the Distributor pulled in over.

In the embodiment of the solvent steam generator according to Figure 3 are in Difference to the embodiment of Figure 2, the heating pipes 2 of the Solventerhitzers. 4 mainly oriented horizontally and that is the flow channel 5.2 limiting straightening plate 6 rotatably formed. The rotation of the straightening plate 6 can be achieved by a mechanical adjustment 6.2, which via a Lever gear on the pivotally mounted at a point 6.1 straightening plate 6 acts. Here, the straightening plate between two positions 5.5 resp. 5.6 are turned, in which the flow channel 5.2 at almost unchanged cross-section of Nozzle throat maximum inflow cross section for the vacuum from the container 1 sucked in aforementioned mixed steam and minimum outflow cross section for the Mixed vapor containing solvent flow has 5.4 (position 5.5) or minimum Inflow cross section for the incoming mixed steam and maximum Outflow cross section for the mixed steam containing solvent flow 5.4 (position 5.6). It can be so depending on the position of the straightening plate 6 and thus dimensioning of Flow channel 5.2, the proportion of mixed steam in the flow channel 5.2 as well the temperature of emerging from the flow channel 5.2 Solvent vapor flow 5.4 can be adjusted.

The structure of two embodiments of the drying device according to Fig.1 contained condensation device can be seen from Figures 4 and 5. at the embodiment of Figure 4 is cold solvent 14 via a with the Shut-off 20.5 connected solvent line 14.3 led to the injectors 11 and in the opposite direction to a passing from below into the condensation chamber 10, Solvent and steam containing mixed steam stream 13 injected. This leads to an advantageous intensive turbulence of the injected cold Solvents 14 with the sucked into the condensation chamber 10 mixing steam flow 13. As a result, the condensation of solvent vapor 14.1 from the Mixed steam flow 13 at the injected cold solvent 14 optimized. The injected Solvent 14 and the condensed solvent vapor 14.1 flow to the drain pan 7 and be pumped with the feed pump 8, while remaining mixed steam 14.2 from the mixing steam flow 13 via the mixing steam line 15 from the Condensation space 10 is removed and led to a mixed steam condenser 16 becomes.

In the embodiment of Figure 5 is cold solvent 14 via the injection nozzles 11, 11.1 injected in the same direction as the mixed steam flow 13 in the latter. Thereby, and by a attached to the entrance of the condensation chamber 10 and the Inlet side of a nozzle limiting straightening plate 12 is a strong flow caused the mixed steam as stream 13 from the interior of the Vacuum container 1 in the condensation chamber 10 sucks. As a result of the same Flow direction of cold solvent 14 and mixed steam 13 is the Condensation stretched slightly. Before the outlet opening 10.3 is at least mounted a baffle 10.2, so that any solvent drops deposited become.

The operation of the device is as follows:
With the vacuum system 18, the vacuum container 1, the mixed steam condenser 16 and the separation tank 17 are evacuated. At the same time, the solvent supply tank 9 draws solvent via the shut-off valves 20.6 and 20.3 and the solvent heater 4 into the vacuum container 1 until the filling level indicator 7.1 is flooded. In the heating phase that follows, the solvent present in the vacuum tank 1 is circulated by the feed pump 8 and heated in the solvent heater 4 to a temperature slightly above a predetermined drying temperature. The heated solvent is heated to normal or possibly higher pressure. Upon discharge of the solvent from the injection openings 5.1 of the Solventverteilkanals 5, the pressure in the solvent 5.3 drops sharply and evaporates a portion of the heated solvent with simultaneous cooling by the amount of its heat of vaporization. The resulting solvent vapor 5.4 condenses on the active part and heats it with simultaneous evaporation of the water contained in the solid insulation, resulting in the formation of the solvent and steam containing mixed steam in the vacuum vessel 1. In the vacuum container 1 resulting and optionally insulating solvent-containing solvent condensate is fed back to the Solventverteilkanal 5 with the feed pump 8 via the solvent heater 4 for evaporation. The solvent 5.3 is advantageously injected at the nozzle throat via the injection openings 5.1 in the flow channel 5.2. 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 vacuum tank 1 is sucked into the flow channel 5.2. The sucked mixed steam mixes with the injected solvent 5.3 and the solvent vapor 5.4 formed during injection. This produces the advantageous effect, on the one hand, of achieving fast and accurate temperature control of the solvent vapor 5.4 entering the vacuum vessel 1, and, on the other hand, circulating the mixing steam at elevated speed turbulently in the vacuum vessel 1 by sucking in the mixed steam into the flow channel 5.2, thereby heating up of the electrical Trocknungsguts 1.1 is significantly accelerated.

If the insulation of the electrical material to be dried 1.1 contain insulating, is this washed out of the condensing solvent and mixes with the Solvent to a solvent / oil mixture. The oil content is in the solvent steam generator not evaporated. Therefore, with continuous removal of mixed steam increases the vacuum container 1 and condensation of the extracted mixed steam in Mixed steam condenser 16, the proportion of oil in the vacuum tank 1 steadily until until practically only pure oil is present. This oil is with the feed pump 8 via Shutoff valve 20.7 brought into the oil tank 19. Thereafter, via the solvent heater 4 solvent again fed into the vacuum tank 1 and in the aforementioned Evaporated way.

The injection nozzles 11, 11.1 is stored in the separation tank 17 cold solvent fed with the feed pump 8.1 via shut-off valve 20.5 and in the Condensation space 10 injected. At the large surface of the injected cold solvent 14 condenses the solvent vapor component into the Condensation space 10 sucked mixed steam 13 to form the condensed solvent 14.1. This can be done in an advantageous manner Enrich water vapor in the condensation chamber 10. It will be less Solvent vapor led to the mixed steam condenser 16. It becomes so energy saved, which on the one hand for heating the solvent and the other to Cooling of the mixed steam condenser 16 is required. The injected solvent and the condensed solvent vapor flow over the drain tank 7 Feed pump 8 and are fed via shut-off valve 20.3 the solvent heater 4.

In the condensation chamber 10 with steam enriched solvent vapor is controlled by the Dampfabsperrventil 20 the mixed steam condenser 16th fed and condensed. This resulting air leakage is with the vacuum system 18th pumped out. The solvent and water-containing condensate is then by means of Sedimentation separated in the separation vessel 17 and the solvent with the pump 8.1 via Shut-off valve 20.5 fed back to the injectors 11, 11.1.

Once the drying material 1.1 is heated to a temperature sufficient for Drying of the solid insulation resp. for washing out if necessary existing insulating oil, the feed pump 8 is turned off and the Steam shut-off valve 20 fully open. By condensation of solvent and Water vapor in the mixed steam condenser 16 is the pressure in the vacuum vessel. 1 lowered and at the same time accumulating in the separation tank 17 solvent condensate with the feed pump 8.1 via the valves 20.4, 20.6 supplied to the solvent reservoir tank 9.

After lowering the pressure in the vacuum tank 1 to such a low level that no Condensation of water and only minimal condensation of solvent in the Mixed steam condenser 16 is obtained, the shut-off valve 21 is closed and the Pressure in the vacuum container 1 with the vacuum pump 18 for a given Period lowered to low vacuum levels. Here are still existing remaining water as well as possibly existing impurities through Condensation removed. After completion of this so-called fine vacuum phase the vacuum tank 1 is vented and then the dried material 1.1 is the Vacuum tank 1 removed.

In the embodiment of the drying apparatus of FIG. 6 is the Vacuum container 1 designed as a housing of a transformer, which is the Drying material, also in this case containing the solid insulation active part 1.1 of the transformer absorbs. The transformer housing 1 is in one Wärmeisolierhaus 1.5 arranged, which are heated by the heat generator 3 can. The heat generator 3 is designed as an air heater. The heating energy is supplied through the tubes 2. Through the tubes 2 heated air is used as a heat transfer medium with the help of a hot air fan 3.1 via a housing feedthrough 3.3 into Heat insulation house 1.5 transported. About a housing bushing 3.2 is air the heat insulating housing 1.5 back to the air heater and again heated. Also in this embodiment of the drying device are the Heating pipes 2 are surrounded by a double jacket and are from the heat generator. 3 heated both the transformer housing 1 and the solvent. in the Difference to the embodiment of Figure 1, the transformer housing. 1 but with cover flanges 1.3 vacuum-sealed openings 1.2, through which openings otherwise the power connections of the active part 1.1 are guided. In one of these openings 1.2 is that of the Solventerhitzer 4 on the Solvent connection line 4.1 Flow channel supplied with hot solvent 5.2 arranged. Instead of a Solventverteilkanals 5 with injection openings 5.1 points in this embodiment, the Solventdampferzeuger now one at the Nozzle throat of the venturi nozzle arranged and in the direction of the nozzle axis aligned injection nozzle 5.7, which via the line 4.1 with hot solvent is fed. Further solvent steam generators each with a flow channel and with one or possibly also with several injectors 5.7 can be provided other openings 1.2 of the transformer housing 1. How out Fig.7 can be taken, the flow channel is 5.2 substantially formed axially symmetrical and is limited by a fixed and the large part around the axis bent Venturiblech 6.3 as well as by the adjustable executed straightening plate 6. On the downstream side is on the straightening plate 6 in addition Deflector 6.4 arranged. By the sheet 6.4 is from the channel 5.2 passing, not evaporated solvent to the wall of the transformer housing. 1 guided and can quickly via a provided in the bottom drain port 1.4 (Figure 6) removed again from the housing 1 and the solvent heater 4 are supplied.

In a further opening 1.2 transformer housing 1 is the condensation chamber 10 arranged. Two embodiments of this condensation space are from the Figures 8 and 9 can be seen, wherein the embodiment of Figure 8 is largely the Embodiment corresponds to Figure 5 and the Fig.9 largely that according to Fig.4. In the embodiment of Figure 8, however, is still an air-cooled Capacitor 23 shown, which with the outlet opening 10.3 of the Condensation space 10 connected via the line 15 and the Mixed steam condenser 16 to form an additional condensation stage for the enriched steam containing mixed steam 14.2 is connected upstream. Air heated in the air-cooled condenser 23 is transferred by a fan 23.1 an inlet opening 23.2 for heating purposes in the Wärmeisoliergehäuse 1.4 transported. in the Capacitor 23 with release of condensation heat for heating the air separated solvent is via an outlet opening 23.3 the drain pot. 7 fed. Remaining mixed steam and air leakage are via an outlet opening 23.4 supplied to the water-cooled mixed steam condenser 16 and accordingly treated the drying device according to Fig.1.

In contrast to the embodiment of Figure 1 is in the drying device 6 shows the assembled transformer in the Wärmeisoliergehäuse first are introduced and instead of housing bushings for the Power connections of the active part 1.1 for carrying the line 4.1 and the Injector 5.7 and to complete the condensation chamber 10 needed Connection flanges 1.3 mounted. With the help of flexible lines 4.1 and 15 and connected to the drain 1.4 condensate drain is the Interior of the transformer housing 1 with the other components of the Drying device connected. To facilitate this assembly work, can the components conveniently on sliding or mobile frame to be assembled. The drying process can now - as in the embodiment the drying device according to Fig.1 described - be performed. in the Difference to the method, as in connection with the embodiment according to 1, is now in the capacitor 23 during condensation heated by mixed steam air into the thermal insulation 1.5 out. This will be the Condensation heat of the solvent deposited in the condenser for Improvement of the efficiency of the drying process in particular Advantageously exploited.

In the embodiment of the drying device according to FIG Invention is in the vacuum tank 1 a generally as a cascade evaporator trained Solventdampferzeuger 24 arranged. Become this steam generator supplied from the outside through the wall of the vacuum vessel 1 solvent and heat. The amount of solvent supplied is by means of a Solventabsperrventils 20.9 controlled. The heat is placed in an outside of the vacuum tank Heat generator 24.2 formed. Solvent vapor 29 formed in the evaporator 24 flows through a solvent vapor outlet 24.1 in the flow channel 5.2. With the Reference numeral 25 is an outside of the vacuum container 1 befindlicher Solvent heater, preheated in the solvent and the preheated Solvent via a Solventabsperrventil 20.8 dosed in the flow channel 5.2 located Solventverteilkanal 5 is performed. Injectors 5.7 of Solventverteilkanals 5 are arranged in the region of the bottleneck of the venturi.

The preheated solvent 5.3 injected in the direction of the solvent vapor stream 29 sucks the Solventdampf from the evaporator 24 due to Jetwirkung and so increases its flow velocity. At the same time, the speed of the Flow channel 5.2 already increased mixed steam flow 30 increases. The from the Flow channel 5.2 passing steam flow 5.4 therefore has a high Flow rate and good turbulence. This results in a higher flow speed and better turbulence of the Vacuum vessel circulating solvent vapor stream than conventional Method. As a result, the drying times are at the same time low Energy consumption reduced. As a result of the Jetwirkung remains the desired high Solvent vapor velocity in the autoclave towards the end of the heating phase receive. This leads to a shorter heating time in the upper temperature range and Accordingly, also provides a small temperature difference over the Drying 1.1 and thus an improved drying quality safely.

In the embodiment of the inventive drying device according to 11, in contrast to the embodiment according to FIG. 10, the solvent vapor stream 29 arranged in an outside of the vacuum vessel 1 external Solvent evaporator 26, for example, a large evaporator or a Downpipe evaporator, produced and via an access port 27 and a Deflection plate 28 containing steam line led to the flow channel 5.2. By the Jetwirkung of injected in the direction of the steam flow 29 heated Solvents are analogous to the embodiment according to FIG. 10 of the solvent vapor the steam line and the mixed steam are sucked out of the autoclave 1 and become so the flow velocity and the turbulence of the steam flow in 5.4 advantageously increased.

LIST OF REFERENCE NUMBERS

1

Vacuum container, transformer housing

1.1

Drying material (electrical device, active part of the device)

1.2

housing openings

1.3

covering flange

1.4

condensate drain

1.5

Wärmeisolierhaus

2

heating pipes

3

Heat generator, air heater

3.1

Hot air fan

3.2, 3.3

Enclosure openings

4

Solventerhitzer

4.1

Solvent connecting line

4.2

Solventzuführleitung

5

Solventverteilkanal

5.1

Injection port

5.2

flow channel

5.3

heated solvent

5.4

solvent vapor

5.5

Location of a straightening plate 6 for maximum entry area of 5.2

5.6

Location of a straightening plate 6 for minimum entry area of 5.2

5.7

injection

6

directional sheet

6.1

Fulcrum of the straightening plate

6.2

Adjustment device for the straightening plate

6.3

venturi sheet

6.4

baffle

7

drain tank

7.1

level indicator

8, 8.1

feed pumps

9

Solvent supply tank

10

Condensation room of heat recuperation

10.1

baffle

10.2

baffle

10.3

outlet opening

10.4

drain sheet

11

injectors

12

directional sheet

13

Mixed vapor stream

14

cold solvent

14.1

Condensed solvent

14.2

Solvent vapor with enriched water vapor

14.3

Solvent line

15

Mixing steam line

16

Mixing steam condenser

17

separation vessel

18

vacuum system

19

oil tank

20

steam regulator

20.1-20.7

Solvent-Ölabsperrventile

20.8, 20.9

Solventabsperrventile

21

Solvent-vacuum shut

22

Water drain valve

23

air-cooled condenser

23.1

fan

23.2

inlet opening

23.3

Outlet opening (solvent condensate)

23.4

Outlet opening (mixed steam)

24

(internal) solvent evaporator

24.1

Solvent steam outlet

24.2

heat generator

25

Solventerhitzer

26

(external) solvent evaporator

27

access nozzle

28

baffle

29

Solvent vapor stream

30

Mixed vapor stream

Claims (17)

Process for drying a product (1.1), preferably solid insulation of an electrical appliance, by the vapor phase method, in which the at least water, optionally additionally insulating oil and impurities, containing good (1.1) in a vacuum container (1) at reduced pressure Condensation of solvent vapor (5.4) is heated and in this case an at least solvent and steam-containing mixed steam stream (13) is formed, which is condensed below and from the condensate water and solvent are deposited, in which method in the vacuum vessel (1) guided solvent at a Is heated, which is above the pressure prevailing in the vacuum container (1), and the heated solvent is introduced into a flow channel (5.2) arranged in the interior of the vacuum container (1), in which it evaporates, characterized in that the heated solvent ( 5.3) with the formation of a hot solvent vapor flow (5.4) in the manner of a V Enturidüse trained flow channel (5.2) is injected. A method according to claim 1, characterized in that the heated solvent (5.3) is injected into a guided through the Venturi nozzle solvent vapor stream (29). A method according to claim 2, characterized in that the solvent vapor stream (29) in a vacuum in the container (1) arranged evaporator (24) is generated. A method according to claim 2, characterized in that the solvent vapor stream (29) in an outside of the vacuum vessel (1) arranged evaporator (26) is generated and passed through the wall into the interior of the vacuum vessel (1). Method according to one of claims 1 to 4, characterized in that the heated solvent (5.3) is injected at the constriction of the Venturi nozzle in the flow channel (5.2). Method according to one of claims 1 to 5, characterized in that the inflow and / or outflow cross section of the Venturi nozzle are changed. Method according to one of claims 1 to 6, characterized in that in the vacuum vessel (1) in the mixed steam flow (13) cold solvent (14) is injected. A method according to claim 7, characterized in that the cold solvent (14) is injected in the flow direction in the mixing steam flow (13). A method according to claim 7, characterized in that the cold solvent (14) is injected against the flow direction in the mixed steam flow (13). Apparatus for carrying out the method according to one of claims 1 to 9, comprising, in addition to the vacuum container (1) receiving the material to be dried (1.1), a solvent steam generator with a flow channel (5.2) arranged in the interior of the vacuum container (1) and a device for condensing the mixed steam flow (13), characterized in that the flow channel (5.2) is designed in the manner of a Venturi nozzle, and in that the solvent steam generator has a device guided into the flow channel (5.2) for injecting heated solvent. Apparatus according to claim 10, characterized in that the injection device downstream of a steam outlet opening (24.1) in the vacuum chamber (1) arranged solvent evaporator (24) or downstream of a steam outlet opening (24.1) of a outwardly into the vacuum tank (1) guided solvent vapor line (27 , 28) which can be fed with solvent vapor from a solvent evaporator (26) arranged outside the vacuum chamber (1). Apparatus according to claim 11, characterized in that the flow channel (5.2) in the region of the steam outlet opening (24.1) is arranged. Device according to one of claims 10 to 12, characterized in that the injection device with a injection openings (5.1) and / or injectors at least in the region of the constriction of the Venturi nozzle in the flow channel (5.2) opening Solventverteilkanal (5) and / or at least one in the area the constriction of the Venturi nozzle in the interior of the flow channel (5.2) held injector (5.7) contains. Apparatus according to claim 13, characterized in that the Solventverteilkanal (5) is designed as an exposed tube. Device according to one of claims 10 to 14, characterized in that the flow channel (5.2) limiting straightening plate (6) is formed adjustable by changing the inflow and / or outflow cross section of the flow channel (5.2). Device according to one of claims 10 to 15, characterized in that in the vacuum container (1) at least one injection nozzle (11) for cold solvent and the mixed steam flow (13) receiving condensation chamber (10) of the condensation device is arranged. Device according to one of claims 10 to 16, characterized in that the vacuum container (1) designed as a housing of a transformer and in a preferably heatable with air Wärmeisolierhaus (1.5) is arranged.

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