APPARATUS CONTAINING A DIELECTRIC INSULATION GAS COMPRISING AN ORGANOFLUORINE COMPOUND

Abstract

The present invention relates to an apparatus for the generation, transmission, distribution and/or usage of electrical energy. The apparatus comprising a housing enclosing an insulating space and an electrical component arranged in the insulating space. The insulating space containing a dielectric insulation gas comprising an organofluorine compound. The apparatus further comprises a desiccant arranged such as to come into contact with the insulation gas. The desiccant contains or essentially consists of lithium bromide.

Claims

1. An apparatus for the generation, transmission, distribution and/or usage of electrical energy, said apparatus comprising a housing enclosing an insulating space and an electrical component arranged in the insulating space, said insulating space containing a dielectric insulation gas comprising an organofluorine compound, the apparatus further comprising a desiccant arranged such as to come into contact with the dielectric insulation gas, said desiccant consists of lithium bromide in solid, crystalline form.

2. The apparatus according to claim 1, wherein the desiccant is obtainable from temporarily heating a native desiccant containing or consisting of hydrated lithium bromide to a temperature of at least 50° C.; and/or that the desiccant is permanently heated during operation of the apparatus to an elevated temperature.

3. The apparatus according claim 1 wherein the organofluorine compound is selected from the group consisting of: fluoroethers and fluoronitriles, and mixtures thereof.

4. The apparatus according to claim 3, wherein the fluornitrile is a perfluoro-nitrile containing four carbon atoms and/or perfluoro-2-methoxypropanenitrile according to the formula CF.sub.3CF (OCF.sub.3) CN.

5. The apparatus according to claim 1, wherein the dielectric insulation gas comprises a fluoroketone containing from four to twelve carbon atoms.

6. The apparatus according to claim 1 wherein the dielectric insulation gas further comprises a carrier gas.

7. The apparatus according to claim 6, wherein the carrier gas comprises air or an air component.

8. The apparatus according to claim 6, wherein the dielectric insulation gas comprises the organo-fluorine compound at a partial pressure corresponding at most to the vapour pressure of the organofluorine compound at the minimum operating temperature of the apparatus, the remainder of the dielectric insulation gas being or comprising the carrier gas.

9. The apparatus according to claim 1, wherein the housing encloses the insulation space in a gas-tight manner.

10. The apparatus according to claim 1, wherein the apparatus further comprising in addition to the desiccant a molecular sieve arranged to come into contact with the insulation gas.

11. The apparatus according to claim 10, wherein the molecular sieve has an average pore size y smaller than 15 Å.

12. The apparatus according to claim 10, wherein the molecular sieve is at least temporarily charged with the organofluorine compound.

13. The apparatus according to claim 10, wherein the molecular sieve has an average pore size y which is at least 2.7 Å.

14. The apparatus according to claim 10, wherein the molecular sieve is a zeolite.

15. (canceled)

16. The apparatus according to claim 10, wherein the desiccant and the molecular sieve provide in combination the dew point inside the apparatus during a maintenance interval of the apparatus of at least 1 year.

17. The apparatus according to claim 1, wherein the electrical component is one of a high voltage apparatus or a medium voltage apparatus or a low voltage apparatus or a direct-current apparatus or a switchgear, or is a high voltage component or medium voltage component or low voltage component.

18. The apparatus according to claim 1, wherein the apparatus is a: switchgear, or part and/or component thereof, gas-insulated line (GIL), busbar, bushing, cable, gas-insulated cable, cable joint, current transformer, voltage transformer, sensor, humidity sensor, surge arrester, capacitor, inductance, resistor, insulator, air-insulated insulator, a gas-insulated metal-encapsulated Insulator, current limiter, high voltage switch, earthing switch, disconnector, combined disconnector and earthing switch, load-break switch, circuit breaker, gas circuit breaker, generator circuit breaker, gas-insulated vacuum circuit breaker, medium voltage switch, ring main unit, recloser, sectionalizer, low voltage switch, and/or any type of gas-insulated switch, transformer, distribution transformer, power transformer, tap changer, transformer bushing, electrical rotating machine, generator, motor, drive, semiconducting device, computing machine, power semiconductor device, power converter, converter station, converter building, and components and/or combinations of such devices.

19. The apparatus according to claim 1 wherein the housing comprises a chamber, in which the electrical component is contained, and a recycling system comprising the desiccant and/or the optionally present molecular sieve, and in that the housing is equipped with a compressor and a pump for pumping the dielectric insulation gas through at least one filter comprising the desiccant and optionally comprising the molecular sieve.

20. The apparatus according to claim 1, wherein the desiccant is or are comprised in a region of the apparatus having a temperature lower than the average temperature present in the apparatus at operational conditions.

21. The apparatus according to claim, wherein the desiccant is or are in the form of pellets and/or tablets.

22. The apparatus according to claim 1, wherein the desiccant is or are comprised in at least one permeable container (4a, 4b′, 4b″, 4b′″) and/or is or are arranged on at least one carrier.

23. The apparatus according to claim 1, wherein the desiccant is or are comprised in at least one permeable container (4a, 4b′, 4b″, 4b′″), the cover of which is permeable at least for water.

24. The apparatus according to claim 22, wherein two or more permeable containers (4a, 4b′, 4b″, 4b′″) are arranged in a frame or holder (6a, 6b) in a manner spaced apart by gaps (8a, 8b′, 8b″, 8b′″) from each other.

25. (canceled)

26. The apparatus according to claim 1, wherein the desiccant does not contain an aqueous solution of lithium bromide.

27. The apparatus according to claim 1, wherein the desiccant does not contain a component selected from the group consisting of: calcium, calcium sulphate, in particular drierite, calcium carbonate, calcium hydride, calcium chloride, potassium carbonate, potassium hydroxide, copper(II) sulphate, calcium oxide, magnesium, magnesium oxide, magnesium sulphate, magnesium perchlorate, sodium, sodium sulphate, aluminium, lithium aluminium hydride, aluminium oxide, activated alumina, montmorrilonite, phosphorpentoxide, silica gel, and a cellulose filter.

28. The apparatus accord to claim 1, wherein the desiccant is chosen such that a water content of the dielectric insulation gas inside the insulating space is kept below an admissible threshold value, in particular below a threshold partial pressure of water vapour of 9 mbar.

29. A method for providing a desiccant to an apparatus for the generation, transmission, distribution and/or usage of electrical energy, the apparatus comprising a housing enclosing an insulating space and an electrical component arranged in the insulating space, the insulating space containing a dielectric insulation gas comprising an organofluorine compound, the apparatus further comprising a desiccant arranged such as to come into contact with the dielectric insulation gas, the desiccant consists of lithium bromide in solid, crystalline form, the method comprising: temporarily heating a native desiccant consisting of hydrated lithium bromide to a temperature of at least 50° C.; placing the desiccant thereby obtained into the insulation space of the apparatus, the heating being performed before, during or after placing the desiccant into the insulation space,

30. A method for operating an apparatus for the generation, transmission, distribution and/or usage of electrical energy, the apparatus comprising a housing enclosing an insulating space and an electrical component arranged in the insulating space, the insulating space containing a dielectric insulation gas comprising an organofluorine compound, the apparatus further comprising a desiccant arranged such as to come into contact with the dielectric insulation gas, the desiccant consists of lithium bromide in solid, crystalline form, the method comprising: permanently heating the desiccant consisting of the solid crystalline lithium bromide, to a temperature of at least 50° C. when being placed inside the insulation space of the apparatus or during operation of the apparatus.

Description

[0100] The present invention is further illustrated by the following examples together with the attached

[0101] FIG. 1 showing the dew point achieved for a system comprising the desiccant according to the present invention in relation to the ratio of the mass of water to the mass of desiccant present, in comparison to other systems having different desiccants;

[0102] FIG. 2 showing a first arrangement of a desiccant and/or molecular sieve in powder form to be comprised in an apparatus according to the present invention;

[0103] FIG. 3a showing a second arrangement of a desiccant and/or molecular sieve in powder form to be comprised in an apparatus according to the present invention in a perspective view;

[0104] FIG. 3b showing a longitudinal section of the arrangement shown in FIG. 3a; and

[0105] FIG. 4 showing the progress of the dew point of a system comprising the desiccant of the present invention over time, synoptically to a specific temperature profile.

[0106] As shown in FIG. 1, the use of the desiccant of the present invention, namely LiBr (presented by circles), allows to maintain a dew point of about −20° C. at a water load of up to 8% and a dew point of −10° C. at a water load of up to 40%. In contrast, the use of the comparative desiccants magnesium sulphate (squares), calcium sulphate (diamonds) and Mg-MOF (triangles) leads to a dew point of 0° C. or above already at relatively low water loads below 2%.

[0107] In the embodiments shown in FIG. 2, 3a and 3b, a desiccant and optionally a molecular sieve is or are comprised in the apparatus or test device. Two exemplary arrangements of the desiccant 1 and the optionally present molecular sieve 2 are shown in these figures.

[0108] According to the specific embodiment shown in FIG. 2, four permeable containers in the form of sachets 4a comprising the desiccant 1 and optionally the molecular sieve 2 in powder form are arranged in a frame 6a, here for example a cuboid frame 6a. The sachets 4a are arranged parallel to each other in a spaced-apart manner, such that between them a respective gap 8a is formed. Specifically, the sachets 4a are in the form of a sheet, the long sides of which corresponds more or less to the height and depth of the frame 6a, respectively. It is understood that any other form suitable for the respective purpose can be used.

[0109] According to embodiments in FIGS. 3a and 3b, the frame 6b is in cylindrical form and comprises an outermost hollow cylinder 10, in which two inner hollow cylinders 12, 14 are arranged concentrically, a middle hollow 12 cylinder and an innermost hollow cylinder 14. In the centre, a rod 16 is arranged coincidingly with the axis of the cylinders 10, 12, 14. Between the rod 16 and the innermost hollow cylinder 14, between the innermost hollow cylinder 14 and the middle hollow cylinder 12, and between the middle hollow cylinder 12 and the outermost hollow cylinder 10, radial gaps 8b′, 8b″, 8b′″, respectively, are formed. In each of the gaps 8b′, 8b41 , 8b′″, a (circumferentially rolled) sachet 4b′, 4b″, 4b′″, respectively, is arranged in a loose manner such that the surface of the sachets 4b′, 4b″, 4b′″ is not in full contact with the surface of the respective cylinders 14, 12, 10 and thus comprises a freely exposed surface area. The bottom end of the frame 6b can be closed, for example by an end plate 18, to safeguard that the desiccant 1 and optionally the molecular sieve 2 does not “fall out” of the gaps 8b′, 8b″, 8b′″.

[0110] In embodiments, any number of cylinders 14, 12, 10 can be selected to provide respective inter-cylinder spaces or gaps 8b′, 8b″, 8b′″ for receiving and holding the desiccant 1 and optionally the molecular sieve 2 in containers 4b′, 4b″, 4b′″, for example in sachets 4b′, 4b″, 4b′″, and for providing insulation-gas-accessible surface areas of the desiccant 1 and the molecular sieve 2.

[0111] FIG. 4 shows the progress of the dew point in a system, into which the desiccant lithium bromide is introduced, which immediately after introduction reduces the dew point to below −40° C. Then 5 ml of water (H.sub.2O) is introduced into the system and leads to a temporary increase of the dew point up to 20° C. In equilibrium state the dew point reaches −20° C. As further shown in FIG. 4, a temporary raise of the temperature from about 20° C. to about 50° C. causes a temporary raise in the dew point from about −20° C. to about 0° C., because surface-near adsorbed or absorbed water is released. After this temporary increase, the dew point again decreases to a value of about −25° C. during holding the temperature at 50° C. When decreasing the temperature in the system to the initial temperature of about 25° C., the dew point even decreases to a value below −40° C., i.e. a value substantially lower than the initial equilibrium dew point of −20° C. This beneficial effect can be explained by diffusion of water from the outer layer of the desiccant lithium bromide towards its core, thus allowing additional water to be adsorbed or absorbed. An embodiment relates to a method for operating the apparatus as disclosed and claimed herein, the method comprising the step of permanently heating the desiccant containing or consisting of lithium bromide, in particular solid crystalline lithium bromide, to a temperature of at least 50° C. and preferably 50° C., when the desiccant is placed inside the insulation space of the apparatus or during operation of the apparatus.

LIST OF REFERENCE NUMERALS

[0112] 1 desiccant [0113] 2 molecular sieve [0114] 4a planar sachet [0115] 4b′, 4b″, 4b′″ rolled sachets [0116] 6a frame, cuboid frame [0117] 6b cylindrical frame [0118] 8a space, inter-planar space, planar gaps [0119] 8b′, 8b″, 8b′″ space, inter-cylinder space, radial gaps [0120] 10 outermost hollow cylinder [0121] 12 middle hollow cylinder [0122] 14 innermost hollow cylinder [0123] 16 rod [0124] 18 end plate