APPARATUS AND PROCEDURE FOR ELIMINATION OF WATER, AIR AND OTHER GASES FROM THE MIXTURE OF SULFURHEXAFLUORIDE (SF6) WITH GAS

Abstract: Apparatus and procedure for elimination of water, air and other gases from their mixture with SF6 gas, where apparatus (A) for slowed down separation of cited ingredients contains thermo-isolated housing (1) whose inside space (3) is filled with cooling substance (3a) in which metal vessel (2) is immerged with the adsorbent that is constructed with connecting tube (5) and connector (6) for connection in operation on the vessel (7) which is some shielded high voltage plant, tank or some other high voltage device containing SF6 gas under over-pressure that has to be purified. The invention also relates to the apparatus (B) for accelerated separation of ingredients, of the same construction as the apparatus (A) only with double connection of the vessel (12) with tubes (15, 15a) and connectors (16, 16a) for connection in operation to the vessel (17), while in the tube (15a) in the feed back circuit is connected the pump (19) with filter (18) for acceleration of the circulation of purified gas SF6. Invention contains the procedure that is performed in the apparatus (A and B), when conduction of SF6 gas in a mixture with other ingredients over the adsorbent, cooled to the temperature over -15 DEG C is done.

Description: APPARATUS AND PROCEDURE FOR ELIMINATION OF WATER, AIR AND OTHER GASES FROM THE MIXTURE OF SULFURHEXAFLUORIDE (SFό) WITH GAS Technical field on which this invention applies The invention belongs to the field of separation in general, t. i. in the field of separation of gasses by adsorption, related to the apparatus and procedure for separation of unwanted substances from the gas sulfurhexafluoride - SFό in high voltage electric plants which contains this gas under over - pressure, as insulator. Under international qualification this patent (MK) 5 is marked: 01D 53/00, B 01 D 53/02, B 01D 53/04 and B 01J 20/00 and B ol J 20/08. Technical problem This invention solves problem of defining the procedure, as well it provides for construction of simple apparatus that will simply and efficiently eliminate by adsorption water, air and other gasses from the gas sulfurhexafluoride - SFό, as the gas under over - pressure which is present as insulator in high voltage electric apparatuses and plants. While the used saturated adsorbates could be easily and simply regenerated without being taken out from the apparatus, and they could be used over and over again. Background art In the present status of technique a number of procedures and devices are known for preparation of gasses, that should be purified by adsorption, for example with immobile adsorbents. One of these procedures and belonging devices are described in YU patent description No. 34 8421 issued on the bases of YU of the patent application P - 1343/71. Here is described the treatment for high dehydration of gasses for ammoniac synthesis, that is performed in two steps, one in the process of cooling, and the other in the process of absorption or adsorption of physical or chemical type. 2 In the second step used substances are active alumino- oxides conditioned for working pressures from 30 to 300 Bars, most convenient from 80 to 200 Bars, over which gaseous mixture is conducted. The procedure that raffinates and dries compressed gasses by self - regenerating adsorption devices with several partitions is known from YU patent P-2210/84. The gas flows at working pressure through the adsorbent, at that gas is raffined and dried, after this narrowing to 1 Bar is done and also airing of partition by dry air for further desorption of moisture from the adsorbent, when it is regenerated. We cite here referent foreign patent papers: US PS No. 4.381.189, US PS No. 4.409.104, US PS No. 4.468.237, US PS No. 4.512.780 and US PS No.4 4.696.681. The process of selective adsorption of methanol and/or water from the mixture of gas dimetilether, methanol and/ or water is known from YU patent P-988/90. Here the mentioned gas mixture is passed through so called molecule sieve with characteristic size of holes that are smaller from diameter of dimetilether molecule, and in the same time larger from diameter of methanol molecule, in the concentration range from 10 PPM to 60 mas. ?of methanol and/or water in the current of dimetilether, at the temperature of adsorption from - 20 to 200 °C and at the pressure from 1 to 4 Bars. Disadvantages of all these procedures, as well as of corresponding to them devices for their realization, are that they are not suitable for implementation in our invention t .i. for raffmation of gas SFό in high voltage electric apparatuses and plants. For this purpose the procedure known from not patent literature for filling of high power electric apparatuses and plants with SFό gas is used, same as in production plants, so on outside sites, that is, in the place of usage. This process is used even if not allowed quantity of following substances: water, air, etc. in SFό gas in the apparatus or plant in exploitation during control is detected. During refilling or filling of apparatus or device, gas SFό is filtered passing through complicated device for filtering. In the same time, part of the apparatus or the plant that contains this gas, is vacuumed several times, and than vacuumed space is filled with some inert gas, nitrate par example. In this manner the water is eliminated from inner surfaces, and, if desired effects were not achieved, the procedure is repeated. This procedure is more difficult to perform in presence of larger quantities of water than allowed in SFό gas and also during decrease of over - pressure in apparatus or plant, because of losses due to bad fittings. 3 Above cited background art solutions from not patent literature have a lot of other disadvantages, main one being insufficient efficiency of dehydration process, as well as indispensable use of complex and expensive devices. Disclosure of invention In the contemporary high voltage electric apparatuses and plants, such as high voltage circuit breakers of high power in distribution plants and others, gas SFό is used under certain over - pressure as dielectric, as it possesses excellent isolation features. As such, in mentioned high voltage circuit breakers of high power, it enables fast and quick extinction of electric spark, so that high voltage plants with this gas could have much less in volume, and require considerably simpler maintenance and are easier in exploitation. But, the gas sulfurhexafluoride - SFό, as contemporary insulating mean, that is more and more in use nowadays, achieves its best insulation performances only at over pressure from 3 to 7 Bar, what demands absolute impermeability of space in which it is placed in the apparatus or the plant. Also, for achieving mentioned isolation performances, gas SFό must be completely purified. And on the bases of laboratory and practical experiments, it should not contain quantities of the water higher than 5 PMM in a new, and 100 PPM in the apparatus and plants already in exploitation. During exploitation, at the forming of electric spark in the environment filled with gas SFό gas degrades, creating poisonous compounds, which do not have its isolation performances. But, these compounds are chemically unstable, so that they relatively soon unify again with basic gas SFό. As well, this gas with water and air makes new stable compounds and then it disintegrates. These compounds diminish considerably its isolation performances. From this we can conclude that presence of water and air in SFό gas, that is used in high voltage electric apparatuses and plants under over pressure, is extremely undesirable. On the bases of above mentioned, as well as on the basis of knowing the disadvantages of already known procedures and devices for purification of the gasses, the goal of this invention is to propose definition of the procedure, as well as the construction of apparatus able to perform it. This apparatus will be able to eliminate, fast and efficiently, water, air and other gasses from their mixture with the gas sulfurhexafluoride - SFό, at that, partial pressures of water and gasses from the air will be led to be zero. 4 During definition of this procedure, it is provided that adsorbent implemented will be zeolites, in which power openings in crystals are smaller than molecules of SFό gas, and larger than molecules of water and gases in the air. Zeolites are alumino-silicates of alkali or earth - alkali elements containing very loosely held water, with well-defined crystal structure. Crystal structure of zeolites constructs by mutual merger certain space form - tetrahedron. Thanks to that, inside zeolites crystal structure exist certain holes with exactly defined sizes of diameter of holes and entry openings, and a regular channel system interconnecting holes. The holes in zeolites crystal's structure are filled by cations and water molecules. By specificity of crystal structure, and by partial mobility of cations and water molecules, are explained numerous physical and chemical features of zeolites, in which belongs electric field as one of the strongest in the whole nature. In the procedure in this invention smaller molecule are drawn through power openings of crystals, then connected in series and extended to dipoles. Meanwhile, molecules of SFό gas, that are larger than openings in zeolite crystal can not be held by its electric field and they pass freely To accelerate the procedure of water separation, as well as air gasses from the mixture with FS6 gas, adsorbents, for example zeolites, are, according to invention, during the process cooled to the temperatures higher than - 45 °C, what decreases kinetic energy of Sf6 gas molecules. The probability is largely increased now, that the smaller molecules will be captured. Molecules of SFό gas, being large, can not be drawn in the holes of zeolite crystal, but they keep enough large kinetic energy to continue its movement. According to our invention, adsorbents in the apparatus for conducting the procedure, zeolites for example, are placed in a dedicated space - vessel (colon), where they are cooled by some refrigerating easily obtainable medium, for example nitrate. Through this vessel, in the process of derivation of water and air gasses from their mixture with the gas SFό, appears this new mixture. This mixture passes over the adsorbent cooled up to certain temperature, zeolite crystal for example, while mentioned temperature of cooling is near to the temperature convenient for obtaining optimal values of kinetic energy of SFό gas. Saturated adsorbents, zeolites for example, are after certain time regenerated. They are, together with vessel, heated up to certain temperature, being vacuumed in the same time. In this way, according to the invention, regenerated adsorbents, zeolites for example, can be used many times in the process. 5 Short description offigures-schemas The invention is described in details on one example of execution out of several possible and shown on schemas where: Figure 1 - represents schematically shown apparatus for separation of water and air gasses, out of smaller quantities of mixture with SFό gas at slowed down adsorption. Figure 2 - represents schematically shown the same apparatus with additional assembly for water and air gasses separation out of larger quantities of mixture with SF 6 gas, at speeded up adsorption and; Figure 3 - represents schematically shown vessel with adsorbents placed in the chambre of the stove for regeneration. Detailed description of the invention In the Figure 1 is shown apparatus A for slow separation of water and air gasses out of their mixture with SFό gas, with retarded adsorption. The apparatus A has thermally isolated housing 1, with isolation layer la, its inner space 3 filled with chilling substance 3a, up to the certain determined level. For taking in the chilling substance 3 a, one side opening 4 with cover 4a, that has openings for balancing the pressure, is made. In the inner space 3 of the housing 1, the metal vessel 2 with adsorbents (zeolites for example) is completely immerged. On the vessel 2 there is a tube 5 with connection 6 for connecting to the vessel 7. These schematic presentation of vessel 7 represents some shielded high voltage plant, tank of the apparatus or the vessel of some other high voltage device, as circuit breaker or the measuring transformer, etc. The vessel 7 contains the gas SFό under over - pressure, which has to be purified by apparatus A, according to this invention. In Figure 2 is shown apparatus B for separation of water and air gasses out of their mixture with larger quantity of SFό gas, which has to be purified by accelerated adsorption. Apparatus B contains, as well as apparatus A, the housing 11, isolated by isolating layer 11a, whose inside space 13 is filled with cooling substance 13a, up to the certain level. For introducing the cooling substance 13a in the space 13, side -opening His made provided with the cover 14a with openings for balancing the pressure. The metal vessel 12 with adsorbents (zeolites, for example) is totally immerged in a substance 13a placed in the inside space 13 of the housing 11. This vessel 12 is constructed with double connection by tubes 15 6 and 15a with connectors 16 and 16a for connection to the vessel 17, as well as to the vessel 7 of the apparatus A. It represents some shielded high voltage plant, tank of the apparatus or the vessel of some other high voltage device, as circuit breaker, measuring transformer, etc. The vessel contains the gas SFό under over - pressure, which has, according to this invention, to be purified by apparatus B. To obtain accelerated separation and derivation of water and air gasses out of larger quantity of their mixture with SFό gas, which is in the vessel 17, in the tube 15a of feed back tube with connector 16a, the pump 19 is connected, as well as the filter 18. These last ones are additional assemblies for forced circulation of purified gas SFό. On the Figure 3 are shown thermo-isolated stove 21 with inside space 21a which contains a metal vessel 2 or 12 filled with saturated adsorbents, zeolites, par example. The vessel 2 or 12 is taken out the apparatus A or B and over its top part, which has one opening 25a, it is connected to the water through ball valve 25 connected to the vacuum pump 23. In the same time on the tube 25a the vacuum meter 24 is connected to follow vacuuming of vessel 2 or 12. The procedure for separation of water and air gasses from their mixture with the gas sulfurhexafluoride - SFό in the apparatuses A and B for slow and fast separation is based on the principle of adsorption by adsorbents, like zeolite, which are cooled to the temperatures over - 45 °C, by nitrate for example. In contact with these adsorbents, kinetic energy of FSόgas molecules is decreasing, what contributes to the multiple acceleration of adsorption process. According to that, adsorbents, zeolites for example, which are in the vessel 2 of apparatus A for slow separation, are cooled to the temperatures over - 45°C, by nitrate for example, that fills the inside space 3 of the housing 1. By connecting vessel 2 over tube 5 via connector 6 to the vessel 7 containing mixture of SFό gas, that has to be purified, this mixture under over pressure flows form vessel 7 through tube 5 in the vessel 2 where it passes over adsorbent crystals (zeolites). During this flow over cooled adsorbents all unwanted substances are eliminated from SFό gas mixture, and it returns back purified through the same tube 5 via connector 5 in the vessel 7. In apparatus B, Figure 2, for fast separation adsorbents, zeolites for example, in the vessel 12 are cooled to the same temperature as in apparatus A by cooling substance 13a that occupies space 13 in the housing 11. Mixture of SFό gas and other elements that has to be 7 purified is led to vessel 12 by tube 15 with connector 16 that connects to the vessel 17. After connection of tube 15, mixture of SFό gas, that is under over- pressure flows to the vessel 12 where it passes over cooled adsorbents, zeolites for example. In aim to speed up the adsorption, t. i. to accelerate separation and derivation of unwanted ingredients from SFό mixture, purified gas SSF6 is fed back with forced accelerated circulation with help of the pump 19 and filter 18, through the tube 15a with connector 16a, in the vessel 17. In this invention, procedure understands that saturated adsorbents, zeolites for example, from the vessels 2 and 12 in apparatuses A and B are after certain period of usage regenerated by elimination of water as well as the gasses from the air out of its crystals. To perform this procedure of regeneration, metal vessels 2 and 12 with adsorbents (Figure 3) are placed inside thermo - insulated stove. After connection of upper part of the vessels 2 and 12 to the opening of tube for vacuuming 25a, the vessels are heated to the temperature of about 300°C. After elimination of the water and air gases out of the adsorbent, and achieved temperature, inside of the vessels 2 and 12 is exposed to deep vacuuming by vacuum pump 23, that is controlled by vacuum - meter 24, connected to tube 25a, that is provided with ball valve 25. Apparatuses A and B and the procedure that goes with them, dedicated for water and air gasses separation out of their mixture with SF 6 gas, are very convenient. Their convenience is in their simplicity and efficiency, as well as in their small size for implementation in all high voltage apparatuses and plants that contain SFό gas as insulator under over - pressure, which has to be purified. This procedure can be implemented the same in new apparatuses and plants as in ones which are already in exploitation. It is understandable, that above described apparatuses A and B, as the subjects of our invention, do not limit the invention, so that there are other possibilities - variants which can be used. Figure 1. - Apparatus and plant for elimination of water, air and other gases from their mixture with gas sulfurhexafluoride - SFό Figure 2. - Apparatus and plant for elimination of water, air and other gases from their mixture with gas sulfurhexafluoride - SFό Figure 3. - Apparatus and plant for elimination of water, air and other gases from their mixture with gas sulfurhexafluoride - SFό

Claims: 8 PATENT CLAIMS 1. The apparatus for elimination of water, air and other gasses out of the mixture with gas sulfurhexafluoride - SFό, that is present as isolation medium in some shielded high voltage electric plant. As for example circuit breaker, measuring transformer, etc., where this gas is under over - pressure represented by vessels (7,17), characterized by it that the apparatus (A, B), consists of housing (1,11) thermo - isolated by isolation material (la, 11a), with side opening (4, 14) for filling, closed cover (4a, 14a) with compensation openings, at that inside space (3,13) of the housing (1, 11) is filled by substance (3a, 13a) for cooling up to the certain level, and in it metal vessel (2,12) with adsorbents is totally immerged and the metal vessel (2) is made with connecting tube (5) with connector (6) in the apparatus (A), for connecting the vessel (7) in operation. 2. The apparatus, regarding claim 1, characterized by metal vessel (12) of the apparatus (B) for fast separation, made with double connection tubes (15, 15a), connectors (16, 16a) for connection during operation of the vessel (17) and in the feed back line in the tube (15a) there is the pump (19) built in and the filter (18) for accelerated circulation of the SF 6 gas. 3. The apparatus, regarding claims 1 and 2, is characterized by adsorbents in metal vessel (2, 12) of apparatus (A, B), for example adsorbents silico - aluminates in crystals, zeolites, par example, with atoms of metal or some other positive element in its grid structure, containing inside strong electric field, while their power openings are smaller than size of molecules of FS6 gas, that is being purified. 4. The apparatus, as in claims 1 to 3, characterized by that the substance (3 a, 13 a) for cooling is located in inside space of thermo-isolated housing (1, 11) of apparatus (A, B), nitrate for example on the temperature higher than - 45°C. 5. The procedure for elimination of water, air gasses and other gasses from their mixture with the gas sulfurhexafluoride - SFό situated in vessel (7) under over - pressure, while the procedure is done in the apparatus (A), as claimed in 1, 3 and 4, characterized by that retarded separation and elimination of ingredients from the mixture with gas FS6 is done by adsorption while it is brought over from vessel (7) by single connection through the tube (5) with connector (6), when it is conducted over adsorbents, zeolites for example, which are contained in the vessel (2), cooled on the temperature over - 45 °C. 6. The procedure, as claimed in 5 and characterized by it that during conduction of mixture of water, air over adsorbents, zeolites for example, and other gasses from their 9 mixture with the gas sulfurhexafluoride - SFό situated in the vessel (17) under over - pressure, while the procedure is done in the apparatus (B), as claimed in 1, 2 and 4, characterized by that accelerated separation and elimination of ingredients from the mixture with gas SFό is done by adsorption while it is brought over from vessel (17) by double connection through the tubes (15, 15a) with connectors (16, 16a), when it is conducted over adsorbents, zeolites for example, which are contained in the vessel (12), cooled to the temperature over - 45°C, while acceleration of circulation of purified gas SF 6 is done through the tube (15a) of feedback connection by pump (19) with filter (18). 7. The procedure, as claimed in 5 and 6 characterized by that uring conducting the mixture of water, air and other gasses with the gas SFό over adsorbents, zeolites for example, is done by introduction of smaller molecules form this mixture through energy openings of their crystals under the influence of their strong electric filed, where their connecting is done in series as well as extension in dipoles, at that molecules of gas SFό, from the mixture, being larger than openings of implemented adsorbents, zeolites for example, can not be held by their electric filed, so that they pass through them. 8. The procedure, as claimed in 5 and 7, characterized by that during conducting the mixture of gas SFό with ingredients, zeolites for example, cooled to the temperature over - 45 °C, kinetic energy is deducted from gas SFό molecules, what accelerates the process of purification considerably with several times increased probability that smaller molecules from ingredients will be introduced in adsorbent's crystals, while the molecules of SFό gas will keep sufficient kinetic energy that will provide continuation of there movement. 9. The procedure, as in claims 5 to 8, characterized by that the regeneration of saturated adsorbents, zeolites for example, which are situated in the vessel (2, 12) of the apparatus (A, B), is done by their heating together with the vessel to the temperature of about 300oC in a thermally isolated stove (21), and that after equalization of the temperature high vacuuming is done by vacuum pump (23) with the control by vacuum - meter (24). 10. Implementation of the apparatus and the procedure for elimination of the water, air and other gasses from their mixture with gas sulfurhexafluoride - SFό, is done by connecting of apparatus (A) by tube (5) with connector (6), as well as with connection of apparatus (B) by tube (15,15a) and connector (16, 16a) on to the vessel (7), t. i. vessel (17) that are some shielded high voltage plant, tank of the apparatus or the vessel of some other high voltage device, for example of circuit breaker, measuring transformer, etc., containing gas SFό under 10 over-pressure, that has to be purified if it contains ingredients of water, air gasses, etc. in the quantities higher than 5 PMM in new and 100 PPM in the plants already in operation.

Inventors: PANTIC VLADIMIR, PANTI&CACUTE
Applicants: PANTIC VLADIMIR, PANTI&CACUTE
Application year: 1999
Main classification: H01H33
IPC codes: B01D53, C01B17, H01H33, H02B13