SE189682C1

SE189682C1 -

Info

Publication number: SE189682C1
Authority: SE
Publication date: 1964-01-01

Description

Uppfinnare: J Men, J Einerkjaer och K Foyn Prioritet begard frail den ma) 1959 (Norge) Foreliggande uppfinning hanfor sig till elektrodhallare for elektriska smaltugnar, som dro utrustade med sjalybrannande, kontinuerliga elektroder. Dessa elektroder brannas som bekant undan f8r undan i den ugn, dar de anvandas, och varje elektrod kommer ador att besta av en undre fardigbrand del och en ovre obrand del, dar den raa elektroclmassan Sr mer eller mindre flytande. Gransen mellan dessa partier, brannzonen, ar forhallandevis skarp och kan Mitt faststallas genom att man sticker en tunn stalstang genom den varma, raa massan tills den stoter mot den harda fardigbranda delen. Inventors: J Men, J Einerkjaer and K Foyn Priority requested from May 1959 (Norway) The present invention relates to electrode holders for electric smelting furnaces, which are equipped with shale-burning, continuous electrodes. As is well known, these electrodes are burned away in the furnace in which they are used, and each electrode will consist of a lower pre-fired part and an upper non-combustible part, where the raw electrolyte is more or less liquid. The boundary between these parts, the fire zone, is relatively sharp and can be determined by sticking a thin steel rod through the hot, raw mass until it abuts the hard, finished burnt part.

StrOmtillforseln till sadana elektroder sker vanligen genom vattenkylda kontaktbackar, som pressas mot elektroden, exempelvis med hjalp av en utvandig klamring, vars tryck mot backarna regleras pa kant att. The current supply to such electrodes usually takes place through water-cooled contact jaws, which are pressed against the electrode, for example by means of an external clamping ring, the pressure of which against the jaws is regulated at the edge of.

I allmanhet kommer brannzonen att ligga I nedersta delen av elektrodhallaren, sa att elektroden blir fardigbrand i hallarens underkant. Brannzonens lage i elektroden Sr starkt beroende av fOregaende belastningsforhallande och elektrodsankningar. Utmed elektrodens periferi kommer den emellertid vanligen ej att stiga hogre an. till hallarens underkant pa. grund av den starka kylverkan fran den vattenkylda Eallaren. Under hallaren erhaller elektroden stromvarme och Sr dessutom utsatt Mr stark varmepaverkan pa grund av flammor i ugnen, och man far darfor mycket stora temperaturgradienter i elektroden i overgangen vid hallarens underkant, vilket kan medfora att sprickor bildas, som i sin tur kunna leda till brott pa elektroden. In general, the fire zone will be located in the lower part of the electrode holder, so that the electrode will be ready to fire at the lower edge of the holder. The position of the fire zone in the electrode is strongly dependent on the previous load ratio and electrode drops. Along the periphery of the electrode, however, it will usually not rise higher. to the lower edge of the hall pa. due to the strong cooling effect from the water-cooled Eallaren. Under the holder, the electrode receives current heat and is also exposed to strong heat effects due to flames in the furnace, and you therefore get very large temperature gradients in the electrode in the transition at the bottom of the holder, which can cause cracks to form, which in turn can lead to breakage of the electrode.

Under branningen kommer elektroden att krympa en del, och detta leder till att man far dalig mekanisk och elektrisk kontakt mellan mantelhylsan och den brAnda elektro- Dupl. kl. 21 h: 21/0 den i zonen omedelbart under backarna, dar den mekaniska pakanningen ar storst och stromtatheten stor. Dalig mekanisk kontakt mellan elektrod och mantel innebar aven mindre saker upphangning av elektroden. During firing, the electrode will shrink somewhat, and this leads to poor mechanical and electrical contact between the jacket sleeve and the burning electro-Duplex. at 21 h: 21/0 the one in the zone immediately below the slopes, where the mechanical packing is greatest and the current density is high. Poor mechanical contact between electrode and sheath also meant minor things hanging from the electrode.

Av dessa skal maste man f8rse elektrodmanteln med invandiga ribbor fOr sdkring av elektrodupphangningen. Dessa tjana samtidigt till fOrstyvning av elektroden och tiverforing av strOm till elektrodens hire. Ribborna utforas vanligen av jarnplat. Med de hOga ternperaturer, som rada i smaltugnen, komma ribborna att smaltas bort och de efterlamna da sprickor i den branda elektroden. Dessa sprickor aro, sarskilt i elektrodens nedre del, utsatta for oxidering, sa att elektroden tares kraftigt i detta omrade. Detta tarande kan leda till att mindre bitar lOssprangas Iran elektroden eller till helt utbildat elektrodbrott, vilket i hog grad okar elektrodforbrukningen. Of these shells, the electrode sheath must be provided with internal ribs to secure the electrode suspension. These simultaneously serve to stiffen the electrode and redirect current to the electrode hire. The ribs are usually made of iron plate. With the high temperatures, which line up in the smelting furnace, the ribs will melt away and the leftover cracks in the burning electrode. These cracks, especially in the lower part of the electrode, are subject to oxidation, so that the electrode is taken up strongly in this area. This action can lead to smaller pieces being leaked to the Iran electrode or to a fully trained electrode rupture, which greatly increases the electrode consumption.

PA grund av de ovan beskrivna olagenheterna dr det av stor vikt att fa. brannzonen sa mycket hOjd, att den alltid befinner sig innanfor hallaren aven efter maximal sank-fling eller nedslappning av elektroden. Detta uppnas enklast genom h8jning av temperaturen I hallaromradet. En sadan hojning av brannzonen kommer vid vanligt hallarutfOrande emellertid aven att medfora vissa olagenheter, i synnerhet i form av dalig elektrisk kontakt mellan backar och mantel. Detta beror pa. att den branda massan ej langre Sr plastisk, sa att elektroden formar sig efter backarna, vilket dr fallet nar brannzonen ligger i hallarens underkant. Vidare komma overgangsmotstanden mellan backar och mantel att stiga pa grund av oxidering och gl8dskalsbildning, som hero pa de hOgre temperaturerna. Due to the illegalities described above, it is of great importance to get. the fire zone is so high that it is always inside the holder even after maximum sinking or relaxation of the electrode. This is most easily achieved by raising the temperature in the hall area. However, such an increase in the fire zone will, in the case of ordinary hall construction, also entail certain irregularities, in particular in the form of poor electrical contact between the slopes and the jacket. This is due to. that the burning mass is no longer plastic, so that the electrode forms after the slopes, which is the case when the fire zone is at the lower edge of the hall. Furthermore, the transition resistance between the slopes and the mantle will increase due to oxidation and scaling, as a result of the higher temperatures.

Flera metoder ha foreslagits for hojning av brannzonen. Enligt ett kant forfarande 2— — h5jes temperaturen i hallaromradet genom att man minskar den vattenkylda kontaktytan mellan elektrod och hallare pa sidant sfitt, att mindre varme bortf5res genom kylvattnet till hfillaren. Denna reducerade kontaktyta uppnas genom att hallarens elektriska kontaktyta antingen utgores av vertikala remsor av valledande material eller genom att man forser en del av hallarens kontaktyta- mot elektroden med en. isolerande belaggning, medan resten av kontaktytan, foretradesvis den nedre delen, utgores av ledande material. Several methods have been proposed for raising the fire zone. According to an edge method, the temperature in the holder area is raised by reducing the water-cooled contact surface between the electrode and the holder on the side surface, so that less heat is removed through the cooling water to the filler. This reduced contact area is achieved by the electrical contact surface of the holder either consisting of vertical strips of conductive material or by forcing a part of the contact surface of the holder against the electrode with a. insulating coating, while the rest of the contact surface, preferably the lower part, is made of conductive material.

Man har aven foreslagit anvandning av tva.- delade hallare, bestaende av tva satser backar, som aro anbragta over varandra, varvid den iivre backsatsen ombesorjer stromtillforseln till elektroden, medan den- undre satsen ombesorjer upphangningen. Den undre backsatsen omgriper da elektrodens fardigbranda del. Genom detta f8rfarande reduceras kylningen av hada hallardelarna till ett mini-Mum, sa att hada backsatserna arbeta vid rodvarme. Da elektrodbranningen forsiggar vid temperaturer pa eirka 420°C, kan man genom att halla hada backSatserna under rod-Tarim fa brannzonen h8jd helt upp i oversta backsatsen. Genom detta forfarande, vilket forutsatter elektroder utan mantel eller elektroder med ometallisk mantel, gar man emellertid miste om den fordelen, att elektrodmassan fir mjuk och plastisk i hallaren, sa. att elektroden kan forma sig efter hfillaren och sakra god mekanisk och elektrisk kontakt. Yidare kan forfarandet lcke anvandas vid elektroder med metalliska inantlar, enar kontaktforhallandena bli alltfor daliga pa grun.d av oxiderings- och glodskalbildning pa manteln. It has also been proposed to use two-part holders, consisting of two sets of jaws, which are arranged one above the other, the upper jaw set providing the power supply to the electrode, while the lower set ensures the hanging. The lower back set then surrounds the finished fire part of the electrode. By this method, the cooling of the hada parts is reduced to a mini-Mum, so that the backsets work at red heat. As the electrode firing takes place at temperatures of around 420 ° C, by holding the backsets below the rod-Tarim, the fire zone can be raised all the way up to the top backset. However, by this method, which presupposes electrodes without sheath or electrodes with non-metallic sheath, one loses the advantage that the electrode mass is soft and plastic in the holder, said. that the electrode can be shaped to the filler and ensure good mechanical and electrical contact. Furthermore, the method can not be used with electrodes with metallic sheaths, otherwise the contact conditions become too poor due to oxidation and scale formation on the sheath.

Ett av skalen till denim efterstravade hOj fling av brdnnzonen ãr att man hittills trott del vara nodvandigt att ha storsta mojliga del av den fardigbranda elektroden innanf5r hallaren med hansyn till stromoverforingen till elektroden. Vi ha emellertid genom farsok och berakningar visat, aft en metallisk mantel av normal tjocklek gott och val kan fora hela str5mmen, dvs. man kan tillfOra hela strOmmen i det omrade, dar massan ar plastisk och obrand, och dar man fdljaktligen uppnar utnaarkt kontakt mellan backar och mantel. One of the denim shells sought after by the fire zone is that it has hitherto been thought necessary to have the largest possible part of the pre-burned electrode inside the holder with regard to the current transfer to the electrode. However, we have shown through farce and calculations that a metallic sheath of normal thickness is good and choice can carry the entire current, ie. you can supply the entire current in the area, where the mass is plastic and non-combustible, and where you consequently achieve close contact between the slopes and the mantle.

Enligt uppfinningen an.vandes en tvadelad hallare, dar den nedre backsatsen, som omgriper elektrodetis harda, ffirdigbranda del ombesorjer upphangningen, medan strommen tillfores genom en iivre backsats, som är sa kraftigt kyld, att elektrodmassan innanf Or hailer sig °brand och plastisk, sa. att elektroden formar sig efter backarna, samtidigt som en utmarkt elektrisk kontakt erhfilles. Den undre backsatsen kan vara vattenkyld, men fir samtidigt flirsedd med varnieisolatiou mot elektroden. Den kan emellertid aven vara okyld, sO. att den sjalv blir sa varm, att den. icke avkyler elektroden. Brannzonen kommer att intaga ett lage mellan den undre varma backsatsen och den ovre kalla backsatsen. Dess lage kan kontrolleras genom att variera varmeisolationen i den undre backsatsen eller genom att variera avstanden mellan backsatserna. According to the invention, a two-part holder is used, in which the lower back set, which surrounds the hard, completely burnt part of the electrode, takes care of the suspension, while the current is supplied through an upper back set, which is so strongly cooled that the electrode mass inside is fire and plastic. . that the electrode forms itself after the jaws, at the same time as an excellent electrical contact is obtained. The lower back kit can be water-cooled, but at the same time flared with varnieisolatiou against the electrode. However, it can also be uncooled, sO. that it itself becomes so hot, that it. does not cool the electrode. The fire zone will occupy a space between the lower hot back set and the upper cold back set. Its position can be checked by varying the thermal insulation in the lower back set or by varying the distance between the back sets.

Eventuellt kan isolationssldktet i hallarens undre backsats skyddas mot slitage med hjalp av en platta av varmebestandigt stal. Genom att utfora dessa plattor av kromnickelstal uppnar man samtidigt, att det oxidskikt, som _ ar karakteristiskt fOr detta material, hindrar strOmgenomgang till den. undre backsatsen. Man kan aven anvanda ett sarskilt isolationsskikt, sa att stramOvergangen frail elektroden till den undre backsatsen blir minimal. Eventuellt kan isolations skiktet skyddas mot kondensation av fOrangat bindemedel genom att det omgives med en tat, tunn platkapa. De tjocka stfilplattorna och den inkapslade isolationen kunna aven hopbyggas till utbytbara enheter. Optionally, the insulation layer in the lower back set of the holder can be protected against wear with the help of a plate of heat-resistant steel. By making these plates of chrome-nickel steel, it is achieved at the same time that the oxide layer which is characteristic of this material prevents current passage to it. lower back kit. You can also use a special insulation layer, so that the tight transition from the electrode to the lower back set is minimal. Optionally, the insulating layer can be protected against condensation of precursor binder by surrounding it with a tat, thin plate sheath. The thick steel file plates and the encapsulated insulation can also be assembled into replaceable units.

Uppfinningen beskrives narmare nedan under hanvisning till den bifogade ritningen. The invention is described in more detail below with reference to the accompanying drawing.

I den enda, schematiska figuren betecknar 1 elektroden och. 2 den metalliska mantel, som omger elektroden. Med 3 betecknas den. ovre satsen backar, som är omgiven av en. vattenkyld klamring 4. ,Strommen kan tillfOras backarna med hjalp av vattenkylda b5jliga kopparledningar, sfisom antydes vid 5. Pa den undre backsatsen är en platta 6 av varmebestandigt stal anbragt, som anligger mot manteln, medan 7 betecknar det varmeisolerande material, som är anbragt mellan plattan och klamringen 8. Upphangningen far den understa bfirande backsatsen är antydd vid 9. In the single, schematic figure, 1 denotes the electrode and. 2 the metallic sheath surrounding the electrode. 3 denotes it. the upper set backs, which is surrounded by a. water-cooled clamping ring 4. The current can be supplied to the jaws by means of water-cooled flexible copper pipes, as indicated at 5. On the lower jaw set is a plate 6 of heat-resistant steel, which abuts against the jacket, while 7 denotes the heat-insulating material, which is placed between the plate and the clamping ring 8. The suspension for the lowest four-point backrest is indicated at 9.

Genom anvandning av den beskrivna hallartypen uppnar man a-ven att genom vanlig sankning av elektroden alltid en fast brand massa erhalles innanfiir den undre backsatsen och de stora temperaturgradienter, som fOrorsaka sprickbildningar, undvikas. Harigenom elimineras risken f5r brott praktiskt taget, vilket i full skala utforda prov bekrafta, och branningsfOrhallandena bli mycket konstanta. By using the type of holder described, it is also achieved that by regular lowering of the electrode a solid fire mass is always obtained within the lower back set and the large temperature gradients which cause crack formation are avoided. This virtually eliminates the risk of crime, which on a full scale challenges tests to confirm, and the firing conditions become very constant.

Den olming i mekanisk hallfasthet, soni erhalles genom elektrodhallaren enligt uppfinningen, medfor att det system av invandiga ribbor, som.hittilIs anvants, kan forenklas avsevart eller helt slopas. Som namnt medfora de spalter, viLka ribborna efterlamna vid avsmaltning, stor avbranning pa elektroden, och praktiska forsok ha visat, att man genom ett forenklat ribbsystem kan uppna en be-sparing i elektrodfarbrukningen pa upp till 30 %. Eventuellt ktmna ribborna ersattas med invandiga klackar eller vartor, som aro pressade i sjalva manteln. The elongation in mechanical strength, which is obtained through the electrode holder according to the invention, means that the system of internal ribs which has hitherto been used can be simplified considerably or completely abolished. As mentioned, the gaps left by the ribs during melting, large burning on the electrode, and practical experiments have shown that a simplified rib system can achieve a saving in electrode consumption of up to 30%. Any cold ribs are replaced with internal heels or warts, which are pressed into the jacket itself.

FOr att forhindra att brannzonen hojes alit- — —3 far Mgt, kan man sarja for att isolationen blir samre i den ovre delen av den undre backsatsen an i dennas nedre del, A. att en viss varmeavledning sker i backsatsens Owe del. To prevent the fire zone from rising alit- - —3 far Mgt, it can be ensured that the insulation becomes smoother in the upper part of the lower back set than in its lower part, A. that a certain heat dissipation takes place in the upper part of the back set.

Vid hallarsystem enligt uppfinningen kan aven den ovre backsatsen anvandas som stoppring vid sankning av elektroden i fOrhallande till hallaren. In the case of the holder system according to the invention, the upper back set can also be used as a stop ring when lowering the electrode in relation to the holder.

Claims

Patent s pr ak:

An electrode holder for self-burning electrodes, wherein the holder consists of two sets of beams, which are arranged one above the other at a certain distance, and wherein the current is applied to the electrode (1) by means of the upper set (3), while the lower set takes care of the suspension, characterized by the coarse back set being so strongly water-cooled that the electrode mass within this set remains raw and plastic, so that the electrode in this area forms after the back set and armed sakerstaller good electrical and mechanical contact between electrode and holder, while the lower back set of the holder is uncooled or thermally insulated from the electrode, so that sufficiently high temperatures are achieved within this back set for the electrode to become solid and ready to burn.

2. An electrode holder according to claim 1, characterized in that the lower, bearing back set is provided with an electrically insulating layer (7), so that the current transition Iran electrode to this back set is minimal.

Electrode holder according to patent claims 1 and 2, characterized in that clamping plates (6) of a heat-resistant material are arranged in the lower back set between the insulating layer and the electrode jacket.

Electrode holder according to claim 3, characterized in that the clamp plates (6) are made of a material, the surface of which is oxidized, whereby the oxide coating will act electrically insulating and reduce the current transition from the electrode to the lower back set to a minimum.

Electrode holder according to patent claims 1 and 2, characterized in that the thermal insulation between the electrode and the lower back set is enclosed in a cap of metallic material.

Electrode holder according to claims 3 and 5, characterized in that a clamping plate (6) and the heat-insulating layer (7) between it and the outer clamping ring (8) in the lower back set of the holder are assembled in sections for replaceable units.

Electrode holder according to claim 1 or 3, characterized in that the insulation in the upper part of the lower back set is coherent in the lower part of this back set, so that some heat is dissipated from the Owe part of this back set. Request publications: Patents freuz Germany 953 995.