WO2010045958A1

WO2010045958A1 - Method for removing corrosive sulfur compounds from a transformer oil

Info

Publication number: WO2010045958A1
Application number: PCT/EP2008/008985
Authority: WO
Inventors: Ivanka ATANASOVA-HÖHLEIN; Peter Heinzig; Vladyslav Mezhvynskiy; Uwe Thiess
Original assignee: Siemens Aktiengesellschaft
Priority date: 2008-10-20
Filing date: 2008-10-20
Publication date: 2010-04-29
Also published as: US20110220552A1; CN102186959A; EP2346971A1; CA2740998A1; BRPI0823168A2

Abstract

The invention relates to a method for removing corrosive sulfur compounds from a transformer oil. By adding a mixture of rare earths comprising aluminum oxide and aluminum silicate to the transformer oil, and enriching the same with an aqueous solution of soluble metal salts, the corrosive sulfur compounds in transformer oil are neutralized with defined heating and cooling phases. The advantage of said method is that no additional chemical components, such as passivators, are added to the transformer oil. When using a tank for receiving the mixture of the rare earths comprising aluminum oxide and aluminum silicate, the reaction can run in the tank. Any aging products that may be present, and the bonded corrosive sulfur compounds are effectively retained within the tank by means of a filter system, and can be disposed of with the tank.

Description

description

Process for removing corrosive sulfur compounds from a transformer sol

The invention relates to a method for removing corrosive sulfur compounds from a transformer sol.

Transformers often use transformers as insulation and cooling media, which have been used to power transformers for many years because of their long-term chemical properties. However, the problem with the use of transformer sols is the presence of natural or added sulfur compounds, which contribute to the oleigen own oxidation stability, especially in the case of non-inhibited transformer sols. As a result, conductive copper sulfide compounds are formed, which deposit preferentially in the paper insulation and impair their insulating properties. This phenomenon is favored especially at high operating and ambient temperatures.

When using unpainted paper-insulated copper conductors within a transformer and under conditions of limited oxygen content, such as when operating a transformer under exclusion of air, transformer cores containing corrosive sulfur-containing constituents will form layers of copper sulfide on the paper insulation. Starting from the copper conductor, copper sulfide layers form inside the insulating paper layers surrounding the copper conductor. As a result, the insulation properties of the paper insulation will in some cases have a lasting effect, so that partial discharges and voltage excursions between the live copper conductors due to the reduced insulation properties of the paper insulation can occur.

These corrosive sulfur compounds, in particular mercaptans and disulfides, are particularly effective in transformers, chokes or passages under certain operating and temperature conditions and reduce the insulating properties of the paper insulation to a considerable extent; in some cases up to only 20 percent of the original stress strength of the paper insulation.

In the prior art, it has hitherto been attempted to suppress the reaction of the corrosive sulfur compounds within the transformer sol with the copper conductor by means of a so-called passivation of the transformer sol, in particular by means of metal passivators with compounds based on benzotriazole, and at the same time to improve the oxidation resistance. The problem here is in particular that the metal passivator can consume during the ongoing operation of the transformer and therefore permanently the available amount of the passivator must be monitored. To what extent long-term passivation alters the properties of the transformer is not known at present.

For example, WO 2005/117031 A2 describes a method and a device for adding a passivator to a conductor. According to the aforementioned patent application, it is proposed to wrap the passivator directly around the conductor and then to electrically encase it with another layer of an electrical insulator and thus to electrically insulate the conductor with the passivator layer as a whole. Furthermore, WO 2007/096709 A2 describes a method for the permanent removal of corrosive components from a transformer sol. According to the aforementioned patent application, it is proposed to remove the transformer oil from a transformer tank and, after heating and adding an acidic liquid, to contact it by means of a sulfide radical trap and then to filter it. After filtering, the so-cleaned transformer oil is returned to the transformer tank.

The same applies to WO 2007/144696 A2 as a method for deactivating corrosive sulfur in transformer sols. According to the invention, it is proposed according to the aforementioned patent application that a sulfide-producing chemical component be added to the transformer sol with corrosive sulfur compounds, so that this chemical component reacts with the sulfur compound and thus the corrosive sulfur compounds are removed from the transformer sol.

Furthermore, DE 10 2005 006 271 A1 describes a process for purifying transformer oil, wherein the transformer oil is first subjected to pretreatment by filtration before it is passed through a bed of an inert inorganic carrier coated with a reactive metal. Subsequently, the transformer oil is filtered through a Bleicherdebett and then fed back to the transformer.

Object of the present invention is therefore to avoid the Nachtei- Ie in the prior art and a method for

Removing corrosive sulfur compounds from a transformer sol provided that is easy to handle and almost complete removal of corrosive sulfur compounds from the transformer sol ensured. A

The object is achieved by the features of the method according to claim 1. According to the invention, a method for removing corrosive sulfur compounds from a transformer torol is proposed in which, with the addition of a mixture of alumina-aluminum silicate-containing rare earths in the transformer sol, this so enriched transformer sol up to heated to 300 degrees Celsius and then cooled by enrichment with an aqueous solution of soluble metal salts.

Subsequently, the transformant enriched with the alumina-aluminum silicate-containing rare earth mixture is again heated to 200 degrees Celsius for at least two hours and then cooled to room temperature.

The heating of the mixture of alumina-aluminum-silicate-containing rare earths activates the matrix adsorption centers by removing the water content. Thereafter, the heavy metal salts contained in the mixture of alumina-aluminum silicate-containing rare earths are dispersed in a little water and the mixture is slowly heated. This produces the heavy metal oxides which are insoluble and firmly bound to the fullerene matrix of the mixture of rare earths containing aluminum oxide and aluminum silicates.

In this way, the adsorbent is prepared. The solution presented here is based on the removal of the reactive corrosive sulfur compounds present in the transformer sol through the use of a wide range of inorganic adsorbents in the range of applications. It is mainly a mixture of alumina-aluminum silicate-containing rare earths and optionally enriched with silver, copper, zinc and / or iron in metallic or oxidic form. In particular, the metal oxides formed by means of the alumina-aluminum silicate-containing rare earth mixture bind the corrosive sulfur compounds and can be collected at a suitable site, with or without the simultaneous removal of oligomeric products, and removed from the transformer torol.

The advantage of this method is that no additional foreign substances, such as passivators, are added to the transformer sol. At the same time, the transformer oil is freed from aging products and from corrosive sulfur compounds. This increases the oxidation capacity and greatly reduces the proportion of corrosive sulfur compounds within the transformer sol, which sustainably increases the service life of the transformer.

It is regarded as an advantage according to the present method that the ratio between the proportion of aluminum oxide and the proportion of aluminum silicate of the alumina-aluminum silicate-containing rare earth mixture is in a ratio of 20:80 to 80:20, preferably 50:50 , The catalytic effect of the alumina-aluminum silicate-containing rare earth mixture is best ensured in the preferred ratio range of fractions.

To provide the largest possible surface area of the alumina-aluminum silicate-containing rare earth mixture, a bulk density of 50 to 80 g / l is advantageously used. In this area, the apparent densities in particular a ^¬ sondere granular alumina aluminum silicate-containing rare earth mixture having an effective surface area for binding of the present in the transformer oil corrosive Schwefelver- bonds. Advantageously, the aqueous solution has a proportion of up to 40% of, in particular, soluble metal salts. In particular, the addition of copper and silver salts leads to improved binding of the corrosive sulfur compounds to the metal salts present in the aqueous solution. As a result, a chemical reaction of the corrosive sulfur compounds present in the transformer sol is avoided with the copper conductor. Advantageously, the pH of the alumina-aluminosilicate-containing rare earth mixture is 6.5 to 9.0. In the above-indicated pH range, the highest possible reaction rate of the metal oxides formed with the corrosive sulfur compounds.

In an advantageous embodiment of the method, it is provided that the ratio of the aluminum oxide-aluminum silicate-containing rare earth mixture to the transformer sol in relation to the respective weights in a ratio of 0.01: 100 to 40: 100, preferably 10: 100, is present. In particular, with the preferred weight ratio of 10: 100 of alumina silicate-containing rare earth mixture to the transformer sol, the highest possible reaction rate based on the respective concentrations is made possible. Advantageously, the rare earth metals according to the third group of the periodic table, including the lantanoides, are part of the rare earth mixture containing aluminum oxide-aluminum silicate. In an advantageous embodiment of the method, the aluminum oxide-aluminum silicate-containing rare earth mixture silver, copper, zinc and / or iron are added. Furthermore, silver nitrate is advantageously added to the aluminum oxide-aluminum silicate-containing rare earth mixture to form silver oxides and / or copper salts for the formation of copper oxides and / or iron oxides. The metal oxides within the alumina-aluminum silicate-containing rare earth mixture are highly reactive and combine with the corrosive sulfur compounds within the transformer and neutralize the corrosive sulfur compounds.

In an advantageous embodiment of the method, it is provided that the alumina-aluminum silicate-containing rare earth mixture is disposed in a container, wherein the container is mounted on a transformer housing and the transformer sol is guided and cleaned in the container, sowxe in the alumina-aluminum silicate-containing rare earth mixture bound sulfides remain as reaction products of the corrosive sulfur compounds in the container. By the reaction of the corrosive sulfur compounds of the transformer sol within the container and the accumulation of bound sulfides in the container these waste products can be disposed of during the removal of the container. At the same time, further contamination of the transformer with the bound sulfides in the container is ruled out, so that almost complete removal of corrosive sulfur compounds from the transformer oil is possible with the aforementioned method.

Advantageously, in the case of complete consumption of the alumina-aluminum silicate-containing rare earth mixture, the container is removed from the transformer housing. In an advantageous embodiment of the method, the container has a display with respect to the existing reactive alumina-aluminum silicate-containing rare earth mixture. As part of a maintenance, the display can be used to determine whether sufficient reactive alumina-aluminum silicate-containing rare earth mixture components are present. conditions and a flawless implementation of the procedure is guaranteed.

Advantageously, a filter system is introduced within the container, the filter system comprising the alumina-aluminum silicate-containing rare earth mixture and the transformer sol is introduced into the filter system. By means of the filter system, in particular the bound sulfides and the Transfomatorolaltprodukte can be easily retained within the filter system and thus collected within the container.

In an advantageous embodiment of the method is provided that the container can be connected to a cleaning device, wherein the cleaning device with the

Transformer housing connectable and the Transformatorol from the Transformatorgehause for cleaning in the cleaning device is transferable and thus in the container outside the Transformatorgehauses the corrosive sulfur compounds are removed.

Further advantageous embodiments emerge from the subclaims.

Example:

An aluminum oxide-aluminum silicate-containing rare earth mixture is present with a ratio of aluminum oxide to aluminum silicate of 50:50 with a density of 600 g / l. The pH is 7.0. One kilogram of the alumina silicate-containing rare earth mixture is added

150 ⁰ C activated and treated after cooling with 400 ml of a 20% aqueous solution of soluble salts of silver, copper, zinc or iron in portions. The mixture is homogenized and gradually to 120 ⁰ C within five Heated for hours. This temperature is maintained for 15 to 20 hours. After cooling, the mixture is stored in the closed vessel. The ratio based on the weights of the active alumina-aluminum silicate-containing rare earth mixture to the treated transformer oil is 0.5: 100 to 10: 100, depending on the aging state and corrosivity of the transformer oil.

Claims

claims

1. A method for removing corrosive sulfur compounds from a transformer sol, comprising the following steps: a) adding a mixture of alumina-aluminum-silicate rare earths into the transformer sol, b) heating the transformatorol enriched in the alumina-silicate-containing rare earth mixture to up to 300 Celsius, c) cooling of the transformer oxide enriched with the alumina-aluminum-silicate rare earth mixture and enrichment with an aqueous solution of soluble metal salts, d) heating to 200 degrees Celsius for at least two hours and subsequent cooling to room temperature.

2. A process according to claim 1, wherein the ratio between the proportion of aluminum oxide and the proportion of aluminum silicate of the aluminum oxide-aluminum silicate-containing rare earth mixture is in a ratio of from 20:80 to 80:20, preferably 50:50.

3. The method according to claim 1 or 2, characterized in that the bulk density of the alumina-aluminum silicate-containing rare earth mixture is 50 to 800 g / l.

4. The method according to any one of claims 1 to 3, characterized in that the aqueous solution is present with up to 40% solution fraction of Losli ^¬ chen metal salts.

5. A process according to any one of claims 1 to 4, wherein a pH of the rare earth mixture containing alumina-aluminum silicate is from 6.5 to 9.0.

6. The method according to any one of claims 1 to 5, in that a ratio of the aluminum oxide-aluminum silicate-containing rare earth mixture to the transformer sol is based on the respective weights in a ratio of 0.01: 100 to 40: 100, preferably 10: 100.

7. A method according to any one of claims 1 to 6, wherein said rare earth metals according to the third group of the periodic table and the lanthanoids are used.

8. The method according to any one of claims 1 to 7, d a d u r c h e c e n e c e s in that there is added to the alumina-aluminum silicate-containing rare earth mixture silver, copper, zinc and / or iron.

9. The method according to claim 1, wherein silver nitrate is added to the alumina-aluminum silicate-containing rare earth mixture to form silver oxides and / or copper salts for forming copper oxides, zinc oxides and / or iron oxides.

10. The method according to any one of claims 1 to 9, characterized in that the alumina-aluminum silicate-containing rare earth mixture is disposed in a container, wherein the container can be connected to a transformer housing and the transformatorol is guided into the container and cleaned, and the sulphides bound in the alumina-aluminum silicate-containing rare earth mixture remain in the container.

11. The method of claim 10, wherein in the case of complete consumption of the alumina-aluminum silicate-containing rare earth mixture, the container is removable from the transformer housing.

12. The method according to any one of claims 10 or 11, d a d u r c h e c e n e c e s in that the container has an indication of the still existing reactive alumina-aluminum silicate-containing rare earth mixture.

13. The method of claim 10, wherein the container comprises a heating device for heating the transformer sol enriched with the alumium-aluminum-silicate-containing rare earth mixture.

14. The method of claim 10, wherein a filter system within the container comprises the rare earth mixture containing alumina-aluminum silicate and the transformer sol is introduced into the filter system.

15. The method according to any one of claims 10 to 14, characterized in that the container is connectable to a cleaning device, wherein the cleaning device to the transformer connectable and the transformer oil from the transformer housing for cleaning in the cleaning device is transferable and thus in the container outside the transformer housing, the corrosive sulfur compounds are removed.