陽極焙燒爐大修臨時(shí)煙道的應(yīng)用operationofanopentypeanodebakingfurnacewithatemporary7

1、 OPERATION OF AN OPEN-TYPE ANODE BAKING FURNACE WITH A TEMPORARY CROSSOVER Esteban Cobo1, Jorge Rey Boero1,Luis Beltramino1, Juan Pablo Artola1,Jean Bigot2,Pierre-Jean Roy2 1Carbon Dept. – ResearchandDev elopment Area -

2、 Aluar S AI C, 2Rio T into Alcan, Aluv al, Centr’ Alp ,BP7 ,38 341 Voreppe, France Keyword s: Anod e baking furnace, refractory construction, fire operation Abstract As part of th e Puerto Mad ryn smelter expansion proj

3、ect, Aluar Aluminio Argentino h as built andnow operates an open type furnace d esignedwithRio T into Alcan AP T ech nology. T h e furnace was built andput into serv ice in two stages, eachof wh ichconsistedof 34 sect

4、ions and2 fires. I n ord er to allow th e erection of th e secondstage andth e connection between bothh alv es of th e furnace, a meth odth at h adprov edto be successful on oth er projects, was applied . A temporary

5、 crossov er was usedto connect two sections at th e endof th e first stage. T h is paper d escribes th e experience gainedd uring th e operation und er th ese cond itions andth e proced ure andprocess control mod ifica

6、tions th at h av e been necessary to maintain th e anod e baking quality. Introdu cti on Aluar Aluminio Argentino operates th e only aluminum smelter in Argentina. I t commencedprod uction in 1974 witha nominal capa

7、city of 140000 t Al/year. After th e retrofitting of th e original Montecatini cells, using an in-h ouse d ev elopedtech nology, andtwo expansion projects, th e plant h as reach edits present capacity of 430000 t Al/ye

8、ar (2010) . During th e last expansion project, a new open type baking furnace was built in ord er to fulfill th e anod e requirements from th e pot rooms. T h e furnace was built in two stages. T h e first 34 sections

9、, 8pits, 192 anod es per section stage, was d riedout d uring S eptember 2007. T h e anod e h and ling equipment andth e firing control system, for th is two fires furnace, were commissionedd uring th e d rying out p

10、rocess. I n th e secondstage, th e furnace was extend edby a furth er 34 sections. T h e d rying out process of th ese sections startedin May 2009. T h e result is a furnace with6 8sections and4 fires. T h e endsect

11、ions of th e first stage of th e furnace h av e been mod ifiedtaking into account th e work requiredfor th e erection andconnection of th e secondstage. T h erefore, th e endh ead walls, h eat insulatedsid ewall in se

12、ctions 5 2 and17 (see furnace sch eme in Figure 1)h av e been d esignedto red uce andfacilitate th e mod ifications requiredfor th e furnace extension. T h e construction of stage 2 began at th e “ new”endof th e comp

13、lete baking furnace, namely sections 34 and35(Figure 1) , andprogressedtoward s th e center of th e furnace, in ord er to minimiz e furnace operation d isruption. T h e stage 2 works, wh ile th e stage 1 furnace was in

14、 operation, createdmany operating constraint wh ichwill be d escribedin th e following paragraph s. Figure 1. S ch ematic v iew of th e furnace d uring temporary connection T h e installation of a temporary crossov e

15、r was one of th e main steps for connecting th e two h alv es of th e furnace d uring construction. T wice before Aluar, th is type of equipment andmeth od ology was usedsuccessfully for anod e baking furnace expansi

16、ons: in 1979 at S abart, andin 198 6at S t Jean d e Maurienne, bothin France. More recently th is tech nique was usedin 2008at T omago Aluminium Company in Australia to rebuildth e old est anod e baking furnace, wh ic

17、hwas startedup in 198 3. T h e concrete tub was retainedwithsome strength ening. T h e h eat insulating andrefractory were ch anged . T h e 74-section furnace was completely rebuilt in a recordfour month s, from th e b

18、eginning of d emolition to laying th e last top block. T h e project was carriedout in two steps withone h alf of th e furnace being rebuilt wh ile th e oth er h alf remainedin operation withth e use of a temporary c

19、rossov er. T h is red ucedth e needfor inv entory andexternal purch ases of bakedanod es. Alth oughth is type of equipment andmeth od ology were usedin th ese projects, some ad justments andimprov ements from th e

20、originally consid eredproced ures were d ev elopedto red uce th e impact in th e furnace operation. T h e purpose of th is paper is to d escribe th e experience of operating an open type furnace witha temporary crosso

21、v er d uring 6month s. As some impacts in th e baking process beh av ior h av e been observ edund er th ese operating cond itions, th e actions wh ichsh ouldh av e been taken to minimiz e th eir effects are d escribed

22、 . 847Light Metals 2011 Edited by: Stephen J. Lindsay TMS (The Minerals, Metals & Materials Society), 2011Figure 4: sch ematic v iew of th e mod ifications at a flue wall (d ownstream sid e)S teps before installat

23、ion Before installing th e temporary crossov er, sev eral mod ifications to th e operation andprocess control routines were mad e. Wh ile th e anod e baking furnace workedwith34 sections, th e nominal fire permutation

24、 cycle was 24 h ours, with2 fires of 17 sections each . I n ord er to remov e th e four endsections from th e process, it was necessary to create a fire with15sections andanoth er with19 sections. T h is meant it was

25、necessary to “ separate”th e endof one fire from th e first section of th e oth er. T o d o th is, th e cycle time of th e two fires was ch angedto 26and28h ours respectiv ely, d uring approximately 45d ays. Once th e

26、 “ long”fire acquiredits configuration andreach edth e endcorner of th e furnace, th e temporary crossov er was installed . T h e cycle time of th e two 15sections fires was th en set at 28h ours. As a consequence of t

27、h e operation withsuchsh ort fires, th e av ailable area for th e load /unloadandroutine maintenance was significantly red uced . S ome measures were th erefore taken in ord er to ensure effectiv e cooling andimprov e

28、 th e working cond itions in th ose sections wh ere refractory maintenance personnel h adto work: ? Removal of one “blowing zone section”, obtaining an extra empty section. T h e two fires configuration was kept with

29、th ree sections for natural preh eating andth ree sections for forcedh eating, but th e blowing z one or th e first cooling area was red ucedfrom four to th ree sections. As a result, th e total cooling time (blowing

30、+ forcedcooling)was red ucedby four h ours. ? Zero point ramp control adjustment. T h e sh ortening of th e controlledcooling area requiredth e ad justment of th e control parameters of th e z ero point ramp, d ecre

31、asing th e ov er pressure set point in th e section upstream of th e last h eating ramp. I n ad d ition, th e lid s of two peeph oles lines next to th e blowing ramp h adto be remov ed . After th is ch ange th e maxi

32、mum temperature measuredon th e surface of bakedanod es d uring th e unload ing process d idnot exceed35 0- 38 0°C, as in normal operation. ? Decreasing of soaking temperature from 1 1 80 ° C to 1 1 6 0 °

33、; C. As th e total soaking time was increasedin 12 h ours, in ord er to compensate th is “ extra”energy input th e soaking temperature was red ucedin 20°C. T h e parameters of th e original andmod ifiedcycles a

34、re sh own in T able I . No impacts on th e baking lev el or oth er properties of th e bakedanod es were observ ed . T able IMain parameters for d ifferent Fire configurations S ections/fire 17 15Cycle time 24 28Pr

35、eh eat area (h r)72 8 4 Fire area(h r)72 8 4 Blowing (h r)968 4 Forcedcooling (h r)485 6S oaking temperature (ºC)118 0 116 0 ? Updating of th e F ire Control S ystem program. T h e S CADA system wh ichmanagedth

36、 e firing control system was mod ifiedin ord er to operate witha 30 section baking furnace withtwo “ sh ort”fires. I n normal operation, th is system, wh ichwas suppliedby I nnov ath erm, uses special control algorit

37、h ms to ad apt to process requirements d uring “ corner andpre-corner”situations. T h e purpose is to h av e an ev en temperature d istribution along th e flues just after th e crossov er ch annel. During th e operati

38、on withth e temporary crossov er th ese mod ules were d isabled , until knowled ge of th e impact of th ese d ev ices on th e process beh av ior was acquired . Op e rati on wi thth ete mp orarycrossov e r I n normal o

39、peration, wh en th e exh aust ramp passes from one sid e of th e furnace to th e oth er, d raugh t set point v alues h igh er th an normal are required , in ord er to compensate for th e energy usedto h eat th e cross

40、ov er insulating lining as well as th e ad d itional pressure d rop. I n some furnaces th e exh aust ramp is mov edd irectly to one section after th e crossov er, wh ere it remains d uring two cycles, increasing th e h

41、 eating time of th e section after th e crossov er. T h is practice is not normally usedat Aluar. I n th e natural preh eating sections, th e flue th ermocouples usedby th e firing control system are placedon th e four

42、thpeeph ole line of th e first section, andconnectedto th e exh aust ramp local panel. As was d escribedabov e, an automatic temperature control algorith m follows th e crossov er situation ad justing th e d raft set-

43、 point v alues withth e object of minimiz ing th e temperature d ev iation between th e flue walls. As a result of th e action of th is mod ule, at th e starting of th e baking process in th e first section d ownstrea

44、m th e crossov er, usually th e temperature is around28 0°C, increasing up to 8 00°C by th e endof th e cycle. I n concord ance withth is temperature ev olution, th e d raugh t set points in th e exh aust con