CA2299860A1

CA2299860A1 - Installation for the vacuum-thermal treatment of materials

Info

Publication number: CA2299860A1
Application number: CA002299860A
Authority: CA
Inventors: Albrecht Melber; Erwin Wanetzky; Jorg Bruckamp; George Molitor
Original assignee: Individual
Current assignee: ALD Vacuum Technologies GmbH
Priority date: 1999-03-04
Filing date: 2000-03-02
Publication date: 2000-09-04
Also published as: JP2000308874A; DE19909441C1

Abstract

An installation for the vacuum-thermal treatment of materials (2) that contain at least one evaporable component features at least one heatable treatment chamber (3, 3.2, 3.3, 3.4, 3.5) with a feed opening (5) located in an overhead position that can be shut by means of a feed valve (6), with a heating device (4), with a vacuum pump, and with a condenser for discharged vapors. At least one additional treatment chamber (31) with a feed opening (34) that is located in an overhead position and can be shut by means of a feed valve (33) is correlated in a serial arrangement with at least one heatable treatment chamber (3, 3.2, 3.3, 3.4, 3.5) and with a heat exchanger (32). Above the treatment chambers (3, 3.2, .3 [sic; 3.3], 3.4, 3.5 and 31) at least one transport chamber (29, 29.2) is located that is open at the bottom and can be moved in a horizontal direction, and into which the height of the material (2) fits completely and that can be connected to each of the treatment chambers (3, 3.2, 3.3, 3.4, 3.5 and 31 ) in a gas-tight and flush alignment manner. A lifting device (27) starts from the transport chamber (29, 29.2) by means of which the material (2) together with the transport chamber (29, 29.2) can be moved between a loading station (35) and an unloading station (36) from one treatment chamber (3, 3.2, 3.3, 3.4 and 3.5) to another treatment chamber (3, 3.2, 3.3, 3.4, 3.5 and 31). It is useful that at least one of the treatment chambers (31) be a cooling chamber in which the heat exchanger (32) is a cooling device.
Fi ure 3

Description

Code: 476-74886 Ref.: 032025.005 INSTALLATION FOR THE VACUUM-THERMAL
TREATMENT OF MATERIALS
Description The invention concerns an installation for the vacuum-thermal treatment of materials that contain at least one evaporable component, in particular for the disposal of waste materials of large electrical devices such as transformers and capacitors that contain PCB-containing insulating oils, which features at least one heatable treatment chamber with a feed opening that is located in an overhead position and can be shut by means of a feed valve, with a heating device, a vacuum pump and a condenser for discharged vapors. PCBs are extremely dangerous substances. But also when disposing of other materials such as soils, dangerous substances like e.g. dioxin (the "Seveso poison") and furan compounds can develop which, under certain processing conditions, may re-form again even after they have been destroyed.
PCBs are polychlorinated biphenyls or polychlorobenzenes with a differing number of chlorine atoms, e.g. with one through ten chlorine atoms and up to 209 isomers with a chlorine content of between approximately 19% and 71 %. They are exceedingly toxic and have a carcinogenic effect. They are mainly absorbed through the skin but also partly through the air and the lungs causing damage to the liver and nervous system as well as changes in the blood pattern. PCBs accumulate in fat tissue. They should not be incinerated if it can be helped.
Incineration requires temperatures of over 1200°C and an oxygen-rich atmosphere since, otherwise, the dioxins (Seveso poison) and furan compounds, which are also toxic, are formed.
Because of their high dielectric constant and their flame-inhibiting effect, as well as because of their good thermal conductivity they have been used for many years as cooling and insulating fluids and as heat transmission oils in transformers and electric capacitors, partly in pure form, and partly as additives to other oils (ROMPP CHEMIE LEXIKON [Rompp Chemical Dictionary], Georg Thieme Verlag, Stuttgart - New York, Vol. M-Pk, 1995, pp.
3243-3245).
Worldwide a large number of such large electrical devices are still used.
Meanwhile, however, the use, storage and even the transportation [of PCBs] have been prohibited in most countries. In spite of high incineration temperatures, the risk of re-combination into toxic substances remains.
The type of disposal depends on the concentration of the PCBs: at a PCB
content of over SO mg/Kg the waste material disposal of the transformers or other electrical devices must be performed in accordance with special procedures. For Germany alone, the amount of special waste was or will be 300,000 tons of PCB waste for the years 1989 through 2000, which consists of 95,000 tons of 1 through 50% PCB, of which 56 tons came from transformers and 17,000 tons from large-scale capacitors (ROMPP LEXIKON LJMWELT [Rompp Environmental Dictionary], Stuttgart-New York, 1993, pp. 536-538).
Installations for vacuum-thermal treatment have so far been configured as single-chamber devices with a rather limited productivity, in particular since the treatment chambers and their installations must follow a time-temperature profile that is quite time consuming:
From DE 44 15 093 A1, such a single-chamber installation is known in which oil residues are removed from randomly deposited hollow bodies such as oil filters of motor vehicles and uncrushed oil cans by means of distillation under vacuum, the so-called VTR
Process (Vacuum-Thermal Recycling). The quantity of residual oil per filter can amount to 250 g. It is useful but not necessary to compress such hollow bodies in a press prior to the VTR
treatment to make better use of the volume of the vacuum chamber. It concerns very small parts.
The re-processing of PCB-containing oils is not addressed.
From EP 0 423 039 A1 and the corresponding DE 690 OS 411 T2, such single-chamber furnaces are known in which non-crumbling material consisting of small pieces is first heated to the final temperature under atmospheric pressure, and then subsequently decontaminated under vacuum. Pieces of wood and metal from transformers and wound plates from capacitors made of paper and aluminum foil are mentioned as materials. Decontaminating transformer wood at 260-280°C, a duration of 18 hours is indicated; 67 hours for the decontamination of wound capacitor plates with carbonization of the paper at 285°C. Disposal of waste materials from complete large-scale installations with a larger portion of insulation oils or total quantity thereof is not described, and not possible either with the known process.
Also, from EP 0 672 743 A1, a mufti-chamber continuous-process installation is known that is, however, rather expensive and still requires long cycling times as the process step with the longest dwell time prevents expeditious passage through the installation.
If the treatment chambers are made as long as is required by the process step requiring the longest dwell time, which is also known from the EP 0 505 278 A1, the installation loses flexibility for other applications since the individual process steps can be of different duration while the length of the chambers cannot be modified. In addition, a continuous process installation completely breaks down in the event that one single chamber experiences a malfunction.
As materials, not only the initially mentioned large-scale electrical devices from the transformer and capacitor group that contain PCB-containing insulation oils can be considered but also soil and other bulk or crumbling materials that are contaminated with toxic or environmentally critical heavy metals, hydrocarbons etc. These materials are usually bad thermal conductors with a high thermal inertia since, in the most inaccessible places, a sufficiently high temperature must be reached to guarantee the complete extraction of certain contaminants.
Due to strict environmental protection regulations, such materials must be processed in large quantities in very different forms and consistencies, and today's capacities by far do not suffice to meet each regulations in the near-term.
Therefore, the invention is based on the development of an installation of the initially described type with a high productivity and flexibility that will make it possible to operate rapidly with differing time profiles as may be required by different materials.
The stated task is solved for the aforementioned installation by means of:
a) at least one additional treatment chamber that is correlated with at least one heatable treatment chamber in a serial arrangement that features a feed opening, which can be shut by a feed valve, and a heat exchanger, b) at least one transport chamber that is open toward the bottom and horizontally movable, that is positioned above the treatment chamber, and that can be connected to each of the treatment chambers in a gas-tight and flush alignment manner, and that is of sufficient height to accommodate the material completely and c) a lifting device starting at the transport chamber by means of which the material together with the transport chamber can be transported from one treatment chamber to the other.
The subject of the invention completely solves the stated task, i.e., the installation features high productivity and flexibility and makes it possible to process rapidly with different time-temperature profiles set according to the material properties.
In this context it can be particularly advantageous - either individually or in combination - i f:
* at least one of the treatment chambers is a cooling chamber and its heat exchanger is a cooler;
* a vacuum pump and a condenser for the discharged vapors are assigned to the cooled treatment chamber, as well;
* at least two horizontally movable transport chambers, each with a lifting device, are located above the treatment chambers, with which they can be connected in a gas-tight and flush alignment manner;
* the feed valves are each positioned in a valve housing that, on its topside, features a sealing seat for the vacuum-tight docking of the transport chambers;
* the directions in which the feed valves can be moved as well as the longitudinal axes of the valve housings have a vertical orientation in relation to the series of treatment chambers;
* the treatment chambers are arranged in a linear series, and there is one loading station at one of its ends and one unloading station at its other end;

* at least part of the treatment chambers are connected to vacuum pumps and condensers, or alternatively, if * the vacuum pumps and condensers are arranged in parallel to the series of treatment chambers in the event that several vacuum pumps and condensers are assigned to a group of treatment chambers;
* the suction lines of the vacuum pumps are connected to the bases of the treatment chambers;
* the valve housings are connected to the vacuum pumps via an additional suction line and the transport chambers, when they are docked onto the sealing seats, can be evacuated through the valve housings;
* the treatment chambers with the heating devices are designed as vacuum induction;
furnaces;
* for the treatment of bulk or granulated material, batch containers are provided featuring an interior and an exterior wall connected to each other by means of a base, in particular, at least one of the walls is perforated, grid-shaped or mesh-shaped;
* the outside of the treatment chamber is surrounded by at least one induction heater;
* the inside of the treatment chamber features at least one device consisting of heating resistors;
* the treatment chamber is positioned between two rows of pillars on which an operation platform rests, and/or if * rails are attached to the operating platform on which the transport chamber can be moved in an upright position by means of wheels.
Effects and advantages of these further embodiments of the subject matter of the invention are more closely explained in the detailed description.
Embodiment examples of the subject matter of the invention are more closely explained based on Figures 1-5.
Shown are:
Figure 1, a vertical section through a single treatment chamber with a docked transport chamber just before the material is lowered into the treatment chamber and the pertinent process schematic, Figure 2, a lateral view of a serial installation consisting of six treatment chambers, one of which is a cooling chamber that interacts with five vacuum induction furnaces, Figure 3, the serial installation according to Figure 2 with differing positions of the two transport chambers and marked transport routes, Figure 4, a batch container in perspective view and Figure 5, a vertical section through a second embodiment example of a single treatment chamber with a docked transport section while the material is being lowered into the treatment chamber.
In Figure 1, a single station 1 of an installation for the vacuum-thermal treatment of material 2 is shown, which in the present case is a transformer containing a charge of PCB-containing insulating oil. Station 1 contains a heatable treatment chamber 3 that is surrounded by a heating device 4 in the shape of an induction coil and that is basically a vacuum induction furnace. A feed opening 5 is located overhead and can be shut by means of a feed valve 6.that is located in a valve housing 7. This valve housing 7 not only extends above the treatment chamber 3, it also protrudes laterally which permits the feed valve 6 to be moved into the dashed position 6a. The valve housing 7 is connected to a vacuum pump 9 via a suction line 8 and can, therefore, be evacuated independently from the treatment chamber 3. Valves 10 and 11 serve to flood with an inert gas and to shut off the line, respectively.
The treatment chamber 3 features a bottom 12 from where a suction line 13 with a large cross section is first routed into a condenser 14 that is positioned up-stream from the vacuum pump 9. A first condenser 15 is a grilling condenser in which a washing fluid lSa is circulated by means of a pump 15b. A second condenser 16 is a surface condenser in which a cooling fluid is circulated through a cooling fluid aggregate 17. The suction line sections 13a and 13b conduct the residual exhaust fumes and vapors to the vacuum pump 9 downstream from which, for safety reasons, another cleaning unit 18, that could e.g. also be an activated carbon filter, is connected via a line 13c. From there the residual gases, with the degree of purity required by law, go to exhaust chimney 19, of which only a sketch is included in the drawing.
The following is also essential: the treatment chamber 3 is connected to a stop valve 21 via a further line 20 to an inert gas line that is not shown in the drawing, and by means of which the treatment chamber, after a first evacuation, can be flooded with an inert gas (e.g., nitrogen [sic]) in order to remove surrounding air. However, the inert gas influx is shut off after the flooding so that no flooding or transport gas is routed or circulated through the treatment chamber. This causes the vapor pressure of the hydrocarbons to gradually increase with the mounting temperature in the treatment chamber. The hydrocarbons accelerate the heating through re-condensation on relatively cooler parts of the material 2. The pressure inside the treatment chamber 3 is sensed by a pressure sensor 22 and controlled via a control unit 23 that acts upon a control valve 24 in the suction line section 13a. This makes it possible to initially maintain a vapor pressure just below the atmospheric pressure and that guarantees ideal heating conditions preventing overpressure from gas or vapor expansion. The control valve 24 will only open fully when the temperature has been reached at which, by means of the full performance [range] of the vacuum pumps, a pressure reduction that is below the specific vapor pressure curves of all of the hydrocarbons, and an abrupt evaporation through boiling become possible.
Above the entire arrangement as described there is a ceiling crane 25 with a crane trolley 26, but it should be mentioned in consideration of Figure 2 that in reality this ceiling crane extends perpendicular to the plane of the drawing.
The crane trolley 26 moves a lifting device 27 with a cable winch 28 that has a lifting cable 28a to which a grab 28b is attached, which can be lifted and lowered independently from the lifting device 27. From the lifting device 27, a transport chamber 29 hangs down that is closed toward its top and open at the bottom and is of such height that the full height of the material 2 is completely contained in it.
The valve chamber 7 features at its top side a sealing seat 30 for the lower edge of the transport chamber 29, which, by means of the lifting device 27, can be docked onto the sealing seat. For this purpose the material 2, in the spatial position shown in the drawing, is moved over the transport chamber by means of the crane trolley 26. In the position shown in Figure l, with the feed valve 6 shut, first the valve chamber 7 and the transport chamber 29 are evacuated via the suction line 8, and subsequently flooded with inert gas via the valve 10.
Comparable conditions are created in treatment chamber 3 by suction line 13 and inert gas line 20. As soon as the person has equalized approximately, the feed valve 6 is moved into the open position 6a and the material 2 is lowered by means of the hook 28b into the treatment chamber 3 to the position 2a marked by a dashed line. The feed valve 6 is closed and the material in position 2a undergoes a vacuum-thermal treatment.
The transport chamber 29 can meanwhile be moved to other positions or treatment chambers and fulfill specific functions there.
As soon as treatment is finished, this transport chamber 29 (or if applicable another available transport chamber 29.2) is moved into the position shown in the drawing again, and the aforementioned motion patterns and pressure conditions are reversed.
As Figure 2 shows, a total of five heatable treatment chambers 3, 3.2, 3.3, 3.4 and 3.5 are positioned, in a serial arrangement, but the serial arrangement does not have to be linear; it can also be polygonal or circular. An installation with the desired capacity can also be accomplished by positioning several such installations in a parallel arrangement.
Another treatment chamber 31 is configured as a cooling chamber containing a heat exchanger 32 inside it, through which a coolant is circulated. This significantly accelerates the sequence of operating steps. Treatment chamber 31 also features an overhead feed opening 34 that can be shut by means of a feed valve 33, an analogous pump that is not shown and a condenser for vapors that are still open at least at the beginning of the cooling phase.

It is obvious that the two horizontally movable transport chambers 29 and 29.2 can be connected to each of the treatment chambers 3 through 3.5 and 31, in a gas-tight and flush aligned manner, and that the material 2 together with the transport chambers 29 and 29.2 can be moved from one treatment chamber to the next. Each of the transport chambers features a lifting device 27 with a cable winch 28, and can be connected to each of the treatment chambers (31, 3 through 3.5) in a gas-tight and flush alignment manner.
As seen from a comparison between Figures i and 2, the moving directions of the feed valves 6 and the longitudinal axes of the valve housings 7 have an orientation that is perpendicular to the series of treatment chambers 31 and 3 through 3.5. The treatment chambers 31 and 3 through 3.5 are arranged in a linear series with a loading station 35 at one end and an unloading station 36 at the other, both located within the active range of the transport chambers 29 or 29.2.
The vacuum pumps 9 and the condensers 14 are arranged in a row that is parallel to the series of treatment chambers 31 and 3 through 3.5.
In each case the valve housings 7 are connected via an additional suction line 8 to the vacuum pumps 9 and the transport chambers 29 and 29.2 can be evacuated through the valve housings 7 while docked on the sealing seats 30.
Figure 3 shows individual steps of reloading processes: a cooled-down material 2 has been brought from the cooled treatment chamber 31 via transport route 37 into the unloading station 36. From the heated treatment chamber 3.5, degasified material 2 is in the process of being raised in order to be subsequently transported immediately via the transport route 38 into the cooled treatment chamber 31 that has just become available. From the loading station 35, still partly cold material 2 has just been lifted up for the purpose of being subsequently taken via transport route 39, into the heated treatment chamber 3.5 that has just become available. It goes without saying that the pieces of material contained in the individual treatment chambers can have very different temperatures depending on the process step, and depending on what point the treatment process has progressed to in each individual case.
Basically, each treatment station can be equipped as shown in Figure 1, i.e.
it can constitute an independently functioning unit that is ready for operation independent from the other treatment stations. However, it is also possible to combine several treatment stations, if necessary all, into a group and to connect them to a central unit "Z," which, in figure 1, is surrounded by a dotted/dashed line. In order to be able to regulate the pressure in each treatment chamber independently, a control valve 24a is provided in the suction line 13 as an alternative to the control valve 24 with a (dashed) connection to the control unit 23.
Figure 4 shows a hollow cylindrical batch container 40 for pourable or free-flowing material featuring an interior wall 41, an exterior wall 42 and a ring-shaped bottom 43 that is entirely or partially provided with perforations 44, as indicated by the cross-hatching. For heat and substance exchange, this has the advantage of providing a large surface/volume ratio with low material depth.
In Figure 5, which shows a second embodiment example of the invention, identical parts or parts with analogous functions as in Figures 1-3 are marked with identical designations. The treatment chamber is of a type in which the heating device 4 has been substituted with an internal resistor heater. The outside of treatment chamber 3 is surrounded by thermal insulation material 45. The suction line 13 exits from the treatment chamber 3 at approximately half its height.
Figure 1 is referred to for the treatment of exhaust gases and vapors.
An operating platform 48 rests on two rows of pillars 46 and 47 and on it, two parallel rails 49 and 50 are mounted that replace the crane bridge 25 shown in Figures 1-3. The transport chamber 29 features four transport rolls 52 over four outrigger legs 51 by which means the treatment chamber 3 can be roiled in a stable position in a direction that is perpendicular to the plane of the drawing.
From the lifting cable 28a hangs a transport cage 53, in which two transformers are positioned on top of each other as the material 2 to be treated, and that rests with its upper edge 53a, in a lowered position on the support element 54. A sealing flange 55 serves as a support for a feed valve, which is not shown here, that closes the treatment chamber 3 during vacuum treatment. The arrangement corresponds approximately with the movement phase according to position 3.5 in Figure 3. The overall height, however, is markedly lower than that in Figures 1 through 3, which has an advantageous effect on the ceiling height of the building required for the installation.
List of desi nations 1 Station 2 Material 2a Position (material) 3 Treatment chamber 3.2 Treatment chamber 3.3 Treatment chamber 3.4 Treatment chamber 3.5 Treatment chamber 4 Heating device S Feed opening 6 Feed valve 6a Position 7 Valve housing 8 Suction line 9 Vacuum pump Valve 11 Valve 12 Base 13 Suction line 13a Section of suction line 13b Section of suction line 13c Line 14 Condensation unit Condenser 15a Washing fluid 1 Pump Sb 16 Condenser 17 Coolant aggregate 18 Cleaning device 19 Exhaust chimney Inert gas line 21 Stop valve 22 Pressure sensor 23 Control unit 24 Control valve 24a Control valve Crane bridge 26 Crane trolley 27 Lifting device 28 Cable winch 28a Lifting cable 28b Hook 29 Transport chamber 29.2Transport chamber Sealing seat 31 Treatment chamber 32 Heat exchanger 33 Feed valve 34 Feed opening 35 Loading station 36 Unloading station 37 Transport route 38 Transport route 39 Transport route 40 Batch container 41 Interior wall 42 Exterior wall 43 Bottom 44 Perforations 45 Heat insulation material 46 Row of pillars 47 Row of pillars 48 Operating platform 49 Rail SO Rail 51 Outrigger leg 52 Transport rolls 53 Transport cage 53a Edge 54 Support elements 55 Sealing flange

Claims

1. Installation for the vacuum-thermal treatment of materials (2, 2a) that contain at least one evaporable component, in particular for the disposal of waste materials from large electrical equipment of the group of transformers and capacitors that contain PCB-containing insulation oils, which features at least one heatable treatment chamber (3,3.2, 3.3, 3.4, 3.5) with an overhead feed opening (5) that can be shut by means of a feed valve (6), with a heating unit (4), a vacuum pump (9) and with a condenser (14) for discharged vapors characterized in that a) at least one heatable treatment chamber (3, 3.2, 3.3, 3.4, 3.5) is correlated in a serial arrangement with at least one other treatment chamber (31) with an overhead feed opening (34) that can be shut by means of a feed valve (33) and that features a heat exchanger (32), b) above the treatment chambers (3, 3.2 3.3, 3.4, 3.5 and 31) at least one horizontally movable transport chamber (29, 29.2) is located that is open toward the bottom into which the material (2, 2a) fits with its total height, and which can be connected to each of the treatment chambers (3, 3.2, 3.3, 3.4, 3.5 and 31) in a gas-tight and flush alignment manner; and in that c) from the transport chamber (29, 29.2), a lifting device (27) starts by means of which the material (2, 2a) can be transported together with the transport chamber (29, 29.2) from one treatment chamber (3, 3.2, 3.3, 3.4 and 3.5) to another treatment chamber (3, 3.2, 3.3, 3.4, 3.5 and 31).

2. Installation according to Claim 1 characterized in that at least one treatment chamber (31) is a cooling chamber and that its heat exchanger (32) is a cooler.

3. Installation according to Claim 2 characterized in that the cooled treatment chamber (31) features a vacuum pump (9) and a condenser (14) for the discharged vapors.

4. Installation according to Claim 1 characterized in that the feed valves (6, 33) are each located in a valve housing (7) that features on its top side a sealing seat (30) for the vacuum-tight docking of the transport chamber (29, 29.2).

5. Installation according to Claim 4 characterized in that the moving direction of the feed valves (6,33) and of the longitudinal axes of the valve housings (7) are perpendicular to the series of the treatment chambers (3.2, 3.3, 3.4, 3.5 and 31).

6. Installation according to Claim 1 characterized in that the treatment chambers (3.2, 3.3, 3.4, 3.5 and 31) are arranged in a linear series and that there is a loading station (35) at one of its ends and an unloading station (36) at its other end.

7. Installation according to Claim 1 characterized in that at least part of the treatment chambers (3.2, 3.3, 3.4, 3.5 and 31) are connected to a common group consisting of vacuum pump (9) and condenser (14).

8. Installation according to Claim 1 characterized in that, if several vacuum pumps (9) and condensers (14) are assigned to a group of treatment chambers (3.2, 3.3, 3.4, 3.5 and 31), the vacuum pumps (9) and the condensers (14) are arranged in a row parallel to the treatment chambers (3.2, 3.3, 3.4, 3.5 and 31).

9. Installation according to Claim 1 characterized in that the suction lines (13) of the vacuum pumps (9) are connected to the bases (12) of the treatment chambers (3.2, 3.3, 3.4, 3.5 and 31).

10. Installation according to claim 4 characterized in that the valve housings (7) are each connected to the vacuum pumps (9) via one additional suction line (8), and that the transport chambers (29, 29.2) can be evacuated through the valve housings (7) while they are docked on the sealing seats (30).

11. Installation according to Claim 1 characterized in that the treatment chambers (3.2, 3.3, 3.4, 3.5) with the heating devices (4) are configured as vacuum induction furnaces.

12 12. Installation according to Claim 1 characterized in that for treating pourable and free-flowing materials, batch containers (40) are provided that feature an interior wall (41) and exterior wall (42) that are connected to each other by means of a base (43).

13. Installation according to claim 12 characterized in that the batch container (40) is provided, at least partially, with perforations (44).

14. Installation according to Claim 1 characterized in that the outside of the treatment chamber (3) is surrounded by at least one induction heater (4).

15. Installation according to Claim 1 characterized in that the inside of the treatment chamber (3) features at least one heating device (4) consisting of heating resistors.

16. Installation according to Claim 1 characterized in that the treatment chamber (3) is positioned between two rows of pillars (46, 47), on which an operation platform (48) rests.

17. Installation according to Claim 16 characterized in that rails (49, 50) are mounted on the operating platform (48) on which the transport chamber (29) can be moved in an upright position by means of transport rolls (52).