EP0462529A1 - Method and device for cleaning of contaminated substances and appliances - Google Patents

Abstract

Method for cleaning substances, appliances and the like which are contaminated with PCB or askarels or the like, in particular electric appliances (10-14), in particular transformers, filled with these liquids serving as insulating means, by means of solvent for the liquid, which is filled into the appliance (10-14) after draining the liquid, and by means of ultrasound, the solvent flowing through a number of substances arranged one behind another in a first direction (flow direction) and, after a start, in steady-state continuous operation at least the upstream first appliance (10) being contaminated with the smallest quantity of liquid, whereas the downstream last appliance (14), on account of the appliances (10-13) previously flowed through, is flowed through after their flowing through with solvent with the highest loading, and at least the first appliance (10) being removed from the series of appliances after the cleaning process and at least one further appliance (10) being added into the series downstream, so that the previously second (11) or third appliance (12) in the series now becomes the first appliance, and so forth. <IMAGE>

Description

The invention relates to a method according to the preamble of claim 1 and an apparatus for performing the method.

In the past, transformers, chokes, capacitors and the like have been filled with insulating liquids which, although they have good insulating properties and are flame-retardant, are nevertheless highly toxic to humans. These are polychlorinated biphenyls, PCBs and such PCB-containing insulating liquids, ascareles, the latter being mixtures of PCBs, triclorobenzene and tetrachlorobenzene.

The simple unloading of transformers, chokes and the like, which contain such liquids, is strictly forbidden and the removal of the liquids from the devices must be carried out according to strict regulations, the liquids being burned in officially approved special incineration plants and the solids being deposited in hazardous waste landfills Need to become. The liquids are removed by incineration without any residual risk to the environment. For solids, on the other hand, methods have been sought for a long time in order to free them of PCB to such an extent that they can be returned to the economic cycle without any further risk to the environment. Cleaning by rinsing is advisable because there are enough solvents that combine high solvent power for PCB with the property of good separability by distillation. The cleaning of the solids can not only be done by rinsing with solvent, because the insulating liquid has penetrated into the pores of the solids and only the surface is cleaned during rinsing, so that deep cleaning is not possible. The fact that large amounts of PCB-containing insulating liquids are still contained in these solid insulating parts is particularly evident when the insulating parts are re-installed in a housing and washed around by a non-PCB-containing replacement insulating liquid. Within a relatively short time, the PCB contained in the insulating parts flows into the new insulating liquid, so that the desired release of the electrical device below the specified limit values has not been achieved.

From DE-OS 36 40 949 it has become known to move insulating parts in a solvent bath with a certain movement speed and for a certain time, heating to a certain temperature taking place which is 20 ° C. below the boiling temperature lies. In addition, ultrasound radiation is carried out at about 30 kHz. This process is carried out in a container with ultrasonic heads on the walls; a cage is inserted into the container, which is rotated and moved up and down. The PCB-soiled insulation parts etc. are inserted in the cage. In addition, circulation of the liquid is achieved by the fact that there are nozzles that spray solvent toward the cage. The solvent pumped out of the container is passed through a heat exchanger and continuously checked for the PCB content. This known arrangement is associated with a gradual heating of the solvent and a gradual reduction in the PCB content in the solvent, which continues until practically a freedom from PCB is achieved in which the insulating parts are considered to be PCB-free.

This version does achieve sufficient cleaning so that the devices or the isolating parts can be easily deposited in normal waste disposal sites. However, it takes a relatively long time because the devices or insulating parts must remain inside the container until they are completely cleaned. Only after complete cleaning can new insulating parts or devices be used.

From US Pat. No. 4,685,972 it has become known to flow through and rinse parts contaminated with PCB with solvent and to filter the contaminated solvent with activated carbon. This takes 30 days, which is not enough, because it turned out that there is still enough PCB in the insulating parts. According to another method specified in the same patent specification, for example, a transformer is first decommissioned and the PCB removed. Then a solvent is filled into the transformer, in which PCB dissolves. The problem is that it is not clear what has to be done with the insulating parts arranged in the transformer.

From US Pat. No. 4,483,717 it has become known to withdraw liquid containing PCB from the transformer housing and to fill it with a liquid not containing PCB. Filling and draining takes place a maximum of three times. The transformer is then closed and steam is passed through, the steam being passed from top to bottom. The temperature conditions within the transformer are such that condensation occurs on the surfaces and in the pores in the lower region. After some time, the transformer is heated to temperatures above the boiling point of the condensed steam, so that a kind of outgassing takes place. This process is also lengthy since only one transformer can be treated at a time.

EP-PS 0 098 811 describes a method for decontaminating electromechanical devices contaminated with PCB with evaporated solvent for PCB, the device, the device and the like being inserted into a housing which is filled with solvent vapor. The pressure and temperature of the solvent vapor are maintained so that the vapor condenses on the top of the device. Here, too, the device in question or the device and the like can only be treated in a single operation, so that the time required for this is relatively high.

From DE-OS 36 15 036 it is known to introduce a liquid solvent for PCB into a transformer and to sonicate the transformer with ultrasonic vibrations or to set the transformer itself in ultrasonic vibrations; then the solvent loaded with PCB is removed from the transformer. Here too there is the problem that only a single transformer can be treated and that the time required is very high.

Measures that are by no means unsuitable for transformers are problematic when devices such as chokes or capacitors (especially the latter) have to be treated. The problem of getting PCB-containing liquids or PCBs out of the capacitor insulation is great, but the time involved is always very long.

The object of the invention is to provide a method of the type mentioned in which a continuous cleaning of several devices, transformers and the like can be carried out without having to interrupt the cleaning process.

This object is achieved according to the invention by the characterizing features of claim 1.

Then several, preferably five, devices, for. B. transformers after draining the insulating agent filled with solvent and arranged in a row one behind the other, fresh solvent is fed to the first device in the row and flows through it; this solvent flowing out of the first device, which is contaminated with insulating liquid, is fed to the next device and flows through this device and is again loaded with insulating liquid. The solvent loaded with the insulating liquid of two devices is fed to a third device, which is also flowed through. The number of devices in such a series is practically only limited by the solubility of the insulating agent in the solvent. After this cleaning process, the first device or the first two devices are removed from the row of devices and one or two further devices are added downstream, so that a cleaned device is continuously removed at the front and an uncleaned device is added to the rear of the row, each device in moves one or two places forward in the row.

At least the first device, i. H. that is, the device or devices which are removed from the row are dried after the cleaning step, while the remaining devices which are still in the row continue to be flowed through by solvents.

In order to clean the internal parts of the devices in a second cleaning step, the same principle of multiple solvent use is used as in the cleaning process (first cleaning step) of the devices. The individual inner parts are gradually fed to a further upstream stage in a kind of countercurrent principle from a stage downstream in the direction of flow; each of the upstream stages has a cleaner solvent than the previous downstream stage, so that ultimately the purest solvent is ultimately present in the upstream first stage and there is practically no longer any contamination by insulating agent possibly contained in the insulating parts set in the first stage the case is.

The device with which the step cleaning of the insulating parts is carried out can be found in the characterizing features of claim 7. The liquid flows through several chambers, which are separated from one another by means of partition walls serving as weirs or also by pipelines with return protection devices, pumps, membranes or the like. This prevents liquid from flowing back from a chamber lying at the rear in the direction of flow into a chamber located therein.

After the insulation parts have gone through these cleaning stages, they are so clean that they can be reused or placed in normal landfills.

Further advantageous embodiments of the invention can be found in the further subclaims.

The invention and further advantageous refinements and improvements of the invention are to be explained and described in more detail with reference to the drawing, in which an exemplary embodiment with transformers of the invention is shown.
The only figure shows a schematic circuit diagram of a cleaning system for transformers.

The system, which is shown in the figure, serves to clean five transformers 10, 11, 12, 13 and 14 arranged in a row one behind the other. In the embodiment shown in the drawing, five transformers are shown; it can of course only be three or more. At the output of each transformer 10 to 14 each connect a line 15, 16, 17, 18 and 19. These lines 15 to 19 are connected to a collecting line 20 which is connected to a distillation device 21 via a line 41. The distillation device 21 separates the PCB-loaded solvent from PCB and introduces it via a line 22 into a disposal container 23, where it is collected.

At the output of the distillation device 21 there is a line 29 which branches into a line 30 and a line 31, the latter being connected to the transformers 11 to 14 via feed lines 32, 33, 34, 35 and 36.

The distillation device 21 supplies, via the lines 29 and 30, cleaning chambers 24, 25, 26, 27 and 28, the output of which is connected to the line 41 via a line 43, a line 44 branching off on the line 43 and leading into the line 31 of the feed line 32 opens. Lines 37, 38, 39 and 40 connect to lines 15, 16, 17, 18 and 19 and are each connected to the next transformer 11, 12, 13 and 14. A line 42 is connected to the transformer 14 and can be connected to the transformer 10 at its input.

The arrangement works as follows:
Fresh solvent is fed from the distillation device 21 to the transformer 10 via the lines 29, 31 and 32. The fresh solvent is loaded with PCB in the transformer 10. This PCB-loaded solvent is supplied via line 37 to transformer 11, from where it is supplied via line 16/38 to transformer 12, etc. until it is has flowed through the transformer 14 and can be fed to the distillation device via lines 19, 20 and 41. Thus, the first transformer 10 receives the cleanest solvent and the solvent is loaded more and more with PCB by the further transformers, so that solvent 14 with the highest PCB concentration or PCB loading emerges from the transformer.

As soon as the transformer 10 is sufficiently cleaned, it is disconnected and a transformer-emptied, solvent-filled transformer takes its place or is connected in its place. This transformer is again given the reference number 10. The cleaning sequence then begins with the transformer 11, so that the clean solvent is supplied to the transformer 11 via the lines 29, 31 and 33. The PCB-containing solvent loaded with PCB from the transformers 11, 12, 13 and 14 then flows via the line 42 into the transformer 10 and from there via the manifold 20 into the distillation device 21. When the transformer 11 is clean then another transformer emptied of PCB takes the place of transformer 11 and the clean solvent is now supplied to transformer 12. After flowing through the transformers 12, 13, 14 and 10, the transformer 11 is flowed through with the solvent loaded by the other transformers, and the PCB-containing solvent flows via the line 16 to the collecting line 20 and from there into the distillation device 21.

The procedure is similar when the cleaned transformers 12, 13, 14 etc. have moved to the first position in the row of treatments.

After the respective disconnected transformer has been dried, it is broken down into its components, such as copper coils, laminated core and connections, etc., which components are either subjected to a second flushing treatment with the same solvent and / or an ultrasound treatment.

For the rinsing treatment, the parts are suitably placed in closed containers which are provided with inlets and outlets for connection to the solvent. The containers can now either be connected alone to a further branch of the line 31 (not shown) or to the first position in the flushing row for transformers, i. H. instead of the transformer 10 or connected to several containers to form a separate cleaning chain that corresponds to the cleaning chain of the transformers 10 to 14.

The pre-cleaned parts, in particular the solid insulating parts, have been removed from the transformers 10 to 14 or at least initially from the transformer 10. These parts are used in chambers 24, 25, 26, 27 and 28. These chambers are separated from one another by walls (without reference numbers) and are connected to one another in such a way that no liquid can flow back from the downstream chambers into the respective adjacent, upstream chamber. That can e.g. B. can be achieved so that the partitions in the direction of the solvent flow are designed as weirs, wherein - seen in the direction of flow - each downstream downstream partition is formed somewhat lower than the previous partition. The same effect can, however, also be achieved with pipelines in which corresponding backflow prevention devices or membranes are installed.

The internal parts made of solid materials and electrically insulating material, which have been removed from the transformer, are first introduced into the chambers 24 to 28, which contain an ultrasound radiation device (not shown), against the solvent flow direction, into the chamber 28, and after a certain time from there into the chamber 27. placed in chamber 26, chamber 25 and chamber 24. In each of these chambers, the parts are exposed to ultrasound for a certain time. They are exposed to sound from five sides in particular, so that the greatest possible cleaning effect is guaranteed. Solvent flows from the distillation device 21 via the line 29 and the line 30 to the chamber 24; it passes through the chambers 24 to 28 in this order and from there reaches the distillation device via the lines 43, 41.

In some cases, it is not necessary to distill the solvent already due to the concentration level of PCB reached in the chambers 24 to 28 at the end of the cleaning. Especially with very clean pre-cleaned parts or with long ultrasonic treatment times, the PCB loading of the solvent is relatively low, so that distillation or processing is not necessary. Since the preparation by means of distillation consumes a lot of energy, the solvent with little PCB contamination is then passed via line 44 to line 31 and from there into transformers 10 to 14 in the appropriate order, thereby achieving an energy-saving process, so that instead of ten Distillation processes only a distillation process is necessary.

The treatment is improved in that the solvent for ultrasound treatment and for rinsing is heated to below its boiling temperature and used at this temperature, as is also known from DE-PS 36 40 949.

In other words: every new transformer is connected to the end of a pre-cleaning chain and continues to advance within this cleaning chain. After the transformer in question has been rinsed at the first point for a certain time, it can be removed from the cleaning chain. The cleaning chain is characterized in that the first transformer 10 is supplied with clean solvent at the beginning of this chain or row, which passes through the various transformers of the chain or row and is thereby increasingly loaded with the pollutant to be removed. As a result, distillation for solvent recovery is only required once for the entire chain, electrical energy is saved for the generation of ultrasonic vibrations and, moreover, the destruction of sensitive solid insulating materials by ultrasound is reduced.

After disconnecting the transformer 10, it is dried and it can be broken down into its components, the copper coil, core sheets and vessel. This disassembly is important for shortening the ultrasonic cleaning performed in the chamber; This procedure also ensures that no PCB splashes endanger skin, clothing or the floor during disassembly. However, this is only permissible under very large safety precautions, which leads to great strain on the operating personnel during dismantling work.

The countercurrent principle in the device with the chambers 24 to 28 also saves considerable distillation power. The individual treatment units are designed so that appropriate vapors can be extracted separately. They do not pollute the hall air in which the system is located and avoid high costs for renewing the air at the workplaces.

There is also the possibility of placing the transformers 10 to 14 under a slight positive pressure using inert gas.

There are non-numbered controllable valves in the individual lines, which can be controlled so that a desired solvent flow is generated through the devices, chambers and lines.

Claims (10)

Process for cleaning substances, devices and the like contaminated with PCB or ascarel or the like (hereinafter referred to only as the device), in particular electrical devices, in particular transformers, filled with these liquids as insulating agents, by means of devices which have been filled into the device after the liquid has been drained off Solvent for the liquid and by means of ultrasound, characterized in that the solvent flows through a plurality of substances, devices and the like arranged one behind the other in a first direction (flow direction), with at least the upstream first device having the least solvent after a start in steady-state operation The amount of insulating liquid is loaded and the solvent flowing out of the downstream, last device is loaded with the highest amount of insulating liquid due to the devices through which the device has previously flowed, and that at least the first device is cleaned after the cleaning process the devices are removed and at least one further device is inserted downstream into the row, so that the previous second or third device in the row now becomes the first device, and so on. A method according to claim 1, characterized in that at least the first device is dried after the cleaning step, while the third and further devices continue to be flowed through by the solvent. Method according to one of claims 1 and 2, characterized in that the inner parts of the devices are additionally cleaned in a further cleaning device. Method according to the preamble of claim 1, and in particular according to one of the preceding claims, characterized in that the inner parts, in particular insulating parts made of solid, removed from the device are used in a cleaning device provided with several stages, that the cleaning device is freed from the solvent in a flow direction is flowed through, whereas the inner parts to be cleaned pass through the stages counter to the direction of flow, so that each part is inserted into the stage at the end of its cleaning and remains there for some time, the fresh solvent being supplied, that after this time this was cleaned in the first stage Part taken out, that in the second stage is converted into the first stage and so on. Method according to one of claims 1 to 4, characterized in that the device or devices removed from the row is or are flushed with air which flows through the device (s) one after the other in the solvent flow direction. Method according to one of the preceding claims, characterized in that any solvent vapors formed in the devices are suctioned off. Apparatus for carrying out the method according to claim 4, characterized in that the containers (chambers) are connected to one another in such a way that no liquid can flow back from the downstream chamber into the upstream chamber. Method according to one of claims 1 to 6, characterized in that the freshly flowing solvent is heated to a maximum possible temperature below the boiling point. Method according to one or more of the preceding claims 1 to 6, 8, characterized in that an ultrasound treatment is additionally carried out in each cleaning stage. Method according to one of the preceding claims, characterized in that the solvent loaded with PCB is processed in a distillation device after flowing through the devices or the chambers.

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