Circuit breaker comprising a metal-organic framework material for co adsorption

Abstract

Embodiments of the disclosure can include a circuit breaker, comprising an enclosure comprising: arcing contacts movable axially relative to each other, between an open position of the circuit breaker in which the arcing contacts are separated from each other and a closed position of the circuit breaker in which the arcing contacts are in contact with each other; and a gas inlet configured to blow an arc-control gas to interrupt an electric arc during movement of the arcing contacts from the closed position to the open position, wherein the arc-control gas comprises at least 80% of carbon dioxide; wherein the enclosure further comprises an adsorbing material, which adsorbs carbon monoxide after ionization of the carbon dioxide during arcing, said adsorber being a metal-organic framework comprising nickel and/or iron.

Claims

1. A circuit breaker, comprising an enclosure comprising: at least two arcing contacts that are movable axially relative to each other, between an open position of the circuit breaker in which the arcing contacts are separated from each other and a closed position of the circuit breaker in which the arcing contacts are in contact with each other, an inlet configured to direct an arc-control gas to interrupt an electric arc during movement of the arcing contacts from the closed position to the open position of the circuit breaker, the arc-control gas comprises at least 80% of carbon dioxide and is substantially oxygen free, wherein the enclosure further comprises an adsorbing material, which adsorbs carbon monoxide that forms after ionization of the carbon dioxide during arcing, the adsorbing material being a metal-organic framework comprising nickel and/or iron.

2. The circuit breaker according to claim 1, wherein the metal organic framework is in a form of particles.

3. The circuit breaker according to claim 2, wherein the particles have a diameter from 1 mm to 10 mm.

4. The circuit breaker according to claim 3, wherein the particles have the diameter from 1 mm to 5 mm.

5. The circuit breaker according to claim 1, wherein the adsorbing material is supported by a ceramic substrate.

6. The circuit breaker according to claim 5, wherein the ceramic substrate is a cordierite substrate or an aluminosilicate substrate.

7. The circuit breaker according to claim 1, wherein the arc-control gas is constituted by carbon dioxide CO2.

8. The circuit breaker according to claim 1, wherein the arc-control gas is a gas mixture comprising CO2 and at least a fluorinated compound.

9. The circuit breaker according to claim 8, wherein the at least the fluorinated compound is chosen among 2,3,3,3-tetrafluoro-2-(trifluoromethyl)-2-propanenitrile, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-2-butanone, 2,3,3,3-Tetrafluoropropene, 1,3,3,3-Tetrafluoropropene and fluorooxirane.

10. The circuit breaker according to claim 8, wherein the arc control gas comprises 90 to 97 percent carbon dioxide and 3 to 10 percent the at least the fluorinated compound.

11. An air-insulated switchgear comprising a circuit breaker as defined in claim 1.

12. A gas-insulated switchgear comprising a circuit breaker as defined in claim 1.

13. The circuit breaker according to claim 1, wherein the adsorbing material adsorb carbon monoxide at a temperature of less than 105 degrees Celsius.

14. The circuit breaker according to claim 1, wherein the arc-control gas comprises at least 90% of carbon dioxide.

15. The circuit breaker according to claim 1, wherein the absorbing material comprises iron and nickel.

16. The circuit breaker according to claim 1, wherein the metal-organic framework comprises a honeycomb structure.

17. The circuit breaker according to claim 1, wherein the adsorbing material does not adsorb fluorinated compounds.

Description

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

(1) The circuit breaker is a medium- or high-voltage circuit breaker Above and below, the terms “medium voltage” and “high voltage” are used in the conventionally accepted manner, i.e. the term “medium voltage” refers to a voltage that is in the range 7.2 kV to 52 kV, whereas the term “high voltage” refers to a voltage that is in the range 52 kV to 800 kV.

(2) The circuit breaker includes a closed enclosure having a certain number of electrical and/or mechanical components that are housed inside said enclosure. The enclosure is a leak-tight enclosure.

(3) The volume of the enclosure can be from 50 L to 1000 L.

(4) The enclosure comprises a gas inlet that is configured to blow the arc-control gas on the electric arc to extinguish it. The gas can be injected in a nozzle. The enclosure also contains a gas outlet.

(5) The adsorbing material is disposed so as to be in contact with the gas flow containing the CO molecules. It can be located close to the arcing contacts.

(6) According to another embodiment, it is located in the gas outlet of the circuit breaker

(7) The arc-control gas in the circuit breaker is a dielectric insulating gas.

(8) It contains at least 80% by volume, and preferably, at least 90% by volume of carbon dioxide. For example, it can be a mixture of carbon dioxide (80-100%) and one or more fluorinated compounds (0-20%). Preferably, it is a mixture of carbon dioxide (90-97, preferably 90-96%) and one or more fluorinated compounds (3-10%, preferably 4-10%). For illustrative purpose, the fluorinated compound can be a compound commercialized by Alstom under the name Novec 4710 (2,3,3,3-tetrafluoro-2-(trifluoromethyl)-2-propanenitrile of formula (CF.sub.3).sub.2CFCN) or Novec 5110 (1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-2-butanone of formula CF.sub.3C(O)CF(CF.sub.3).sub.2). It can also be 2,3,3,3-Tetrafluoropropene (HFO-1234yf), 1,3,3,3-Tetrafluoropropene (HFO-1234ze) or fluorooxirane.

(9) Two fluorinated compounds, such as heptafluoroisobutyronitrile and tetrafluoromethane, could also be used in association.

(10) It should be noted that the adsorbing material could be used for gases with lower CO.sub.2 amount. As long as there is CO.sub.2 in the gas mixture, CO can be formed due to arcing in high-voltage circuit breaker.

(11) According to a further embodiment the gas mixture comprises oxygen. The oxygen can further facilitate the reduction of harmful byproducts. For example, the gas mixture contains at least 80% of a mixture of carbon dioxide and oxygen. Wherein the oxygen content is preferably in the range of 1% to 25%.

(12) In another embodiment, the gas could consist of carbon dioxide.

(13) The arc-control gas is oxygen-free. By oxygen-free, it should be understood that the arc-control gas contains less than 0.1% by volume of oxygen gas, and preferably less than 0.02%.

(14) Advantageously, the dielectric insulating gas is present in the equipment in entirely gaseous form whatever the utilization temperature of the equipment. It is therefore advisable for the pressure of the gas inside the equipment to be selected as a function of the saturated vapor pressure (SVP) presented by the gas at the lowest utilization temperature of said equipment.

(15) During arcing, carbon dioxide is ionized into carbon monoxide. The amount of formed CO depends on the physical conditions of the operation and the chemical reaction involved in the process. It varies from few ppm up to few %, from example from 1 ppm to 5%.

(16) Carbon monoxide neutralization is achieved using an adsorbing material. The adsorbing material is a MOF.

(17) Every time an electric arc is extinguished and carbon monoxide is formed, the adsorbing material adsorbs it.

(18) The performance and the application of a MOF depend on the metal and on the ligand. Selectivity can evolve between 10% (very low selectivity to CO) and 100% (exclusive adsorption of CO). In the present invention, the structure of MOFs has been modified in order to be selective to CO instead of CO.sub.2 in the operation conditions of a medium- or high-voltage circuit breaker.

(19) A MOF with iron and/or nickel presents adsorption selectivity to CO in a gas mixture comprises CO and CO.sub.2

(20) The tests consist in following during minutes/hours/days the evolution of the amount of CO (and CO.sub.2) within an airtight test cell containing the sample (gas mixture) in contact with the MOF. Several MOFs materials of the invention have been successfully performed and tested using spectroscopy and gas chromatography.

(21) The adsorbing material can be a powder of particles. The particles may a have a diameter of few millimeters, from example 1 mm to 10 mm, preferably from 1 mm to 5 mm.

(22) The MOFs material of the present invention may be coated to the surface of any suitable substrates.

(23) Advantageously, the substrate presents a high specific surface. For example, the substrate can be a substrate with a “honeycomb” or “monolithic” shape. The honey comb structure is also useful to trap the carbon powder.

(24) The substrate can be a ceramic such as a cordierite substrate or an aluminosilicate substrate.

(25) Alternatively, the neutralization material can be dispersed on a particulate support, such as pellets or particles or the like.

(26) This kind of MOFs can be used in situ in medium- or high-voltage circuit breaker.

(27) When an electric arc is formed, a portion of the fraction of CO.sub.2, which is present in the gaseous state inside the enclosure, is broken down into molecular species of smaller molecular mass and, therefore, of smaller size than CO.sub.2. This has the effect of raising the total pressure that exists inside the enclosure, while lowering the partial pressure of the CO.sub.2 to below its SVP. The carbon monoxide molecules thus formed in this way are trapped by the adsorbing material, and this has the effect of returning the partial pressure of CO.sub.2 to a value equal to its SVP.

(28) The man skilled in the art will be able to select the appropriate amount of adsorbing material according to the volume of CO gas to be treated and the inner geometry of the involved enclosure of the circuit-breaker. For example, the amount of adsorbing material is calculated as function of the potential amount of CO formed within the circuit breaker after arcing simulated over the circuit breaker lifetime. It depends on the energy of arcing and so on the circuit breaker type. For illustrative purpose, maintenance can be expected every 20 years, during which the circuit breaker is opened and the adsorbing material may then be replaced by a new one if necessary.

(29) The circuit breaker according to the invention has a compact structure. The concepts of the various embodiments described above can be effectively applied to various kinds of circuit breaker, such as for example circuit breakers with an interruption chamber of the axial- or transverse-blast type or of the mixed transverse-axial blast type.

(30) For illustrative purposes, the circuit breaker can be used in any electrical device employing CO2 gas electric insulation, namely an electrical transformer, an electricity transporting or distributing line, a set of busbars, a switch, a connector/disconnector (also called switchgear), a unit combining a circuit breaker with fuses, a grounding switch, or a contactor.

(31) The circuit breaker is particularly valuable for air-insulated switchgear (AIS) or gas-insulated switchgear (GIS), and more preferably for high-voltage AIS or GIS.