CA1236509A - Furnace - Google Patents
FurnaceInfo
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- CA1236509A CA1236509A CA000464674A CA464674A CA1236509A CA 1236509 A CA1236509 A CA 1236509A CA 000464674 A CA000464674 A CA 000464674A CA 464674 A CA464674 A CA 464674A CA 1236509 A CA1236509 A CA 1236509A
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- lining
- current
- working surface
- elements
- furnace
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Abstract
FURNACE
ABSTRACT
A characteristic feature of the present invention resides in that additional current-conducting elements are envisaged which fail to exit on the working surface of the furnace refractory lining. These elements are connected to pole terminals of a current source of op-posite polarity relative to the connection of the main elements of the corresponding working surface.
ABSTRACT
A characteristic feature of the present invention resides in that additional current-conducting elements are envisaged which fail to exit on the working surface of the furnace refractory lining. These elements are connected to pole terminals of a current source of op-posite polarity relative to the connection of the main elements of the corresponding working surface.
Description
~;~3~
FUl~ACE
'~his invention relates to the art of preventing a refractory furnace lining from wear by applying an elect-ric field. More particularly, it relates to industrial furnaces u~ed in metallurgy and glass production.
Major reaso~s for refractory lining wear are u3ually heat load~ and high-temperature corrosion induced b~ melts a~d gase~ accompanying the burning of a fuel, as well as by ~he liquid and gaseous melting products.
Heat loads exerted on the lining are di~tinguished by non-uniform heat ~luxes and temperature patterns, as well a~ by ~requent -temperature v~riation3, resul-ting in mecha-nic~l ~trains in the lining and eventually in ~pallin~
thereof.
Corro~ion affects the structure of the lining working ~urface in contact with the melt and furnace ga~eou~ at-mosphere to re~ult in deterioration o~ i-ts ~trength and in turn in a considerable a¢celeration o~ spalllne.
Du~ing furnace operation -the surface of the refractory material ba~ed on such heat-resi~ta~t metal oxides as ~1203, CaO, MgO, ZrO a~d the like is impregnated with various substance~, particularly molten metal~ and sla~ in melting furnaces, molten heat-transfer medium in hea-ting furnQces, and in mo~t cases with g~seous products. This gives rise to the formation o~ an area of complex chemical composition, which may h~ve the proper-tie~ of both semicon-du¢tors and solid electrolytes. ~he temperature of this . ~
~L23~S~
area in non-uniform at various points; that i~ ~ome areas are heated more than the others. In tu~n, -thi~
promotes the appearance of a thermoelectromotive ~orce (thermal em~), which induces an electric current in the lining to cause an excessive electrochemical corrosion of the refractory.
~ he magnitude and direction of this electromotive force depend on t~e chemical compo~ition of the refractory lining impreg~ated with the ~urnace produc-ts, and on the temperature difference. If the temperature difference is ne~ligeable, it can be con~i~ered that that E = ~ ~ T, wh~re E is the magnitude of the thermal emf between two pointa, ~ r is the temperature di~ferenoe between the~e points, and ~ i~ a constant eoefficient -takîng into account the compo~ition of the refrac-tory material. l~ormal-ly, the ~urnace operation i~ accomp~nied by a thermal emf of botweerl 0.5 and 2.0 V.
~ he n~ture and rate of elecSrochemical corrosion vary a~d depend o~ the conductivit~ of the area throu~h which the electric current pa~es. As a rule, both conduction by electrons and ionio co~duotion take place.
A multitude of techniques are employed for fighting Gorrosion of the furnace refractory lining.
; One such -technique involves immer~io~ in a melt bath o~ at least one electrode o~ a aurable material, wherea~
the zirconium~o~ide b~sed re~ractoriea to be protected are brought into contact with metal conductors for a continuous ~X3650~
em~ produced by an ex-ternal ~ource to ari~e between the~e conductors and the electrodes immersed in the bath, whereby an electric current ~low~ from -the electrode to the refractories to be corrosion-protected. ~he em~ is adjusted so as to provide an electrolytic current having a den~ity ~t the surface o~ the refractory on the order of 10 mA/cm2.
~ here~ore, corrosion is inhibited due to ionic exch~nge c~used by a difference between the chemic~l po-te:ntials o~ the molten sub~tance and the surface of the refractory.
Inherent in the above technique is a di~advantage re~iding in that it i~ applicable exclusively to re~rac-torie~ based on zirconium o~ide. In addition, it ~ails to provide for a substantial increase in the durability of the refractory lining, since i-t ac-t~ to defer only one rather than all kinds of corrosion. Another di~adva~tage i~ that the qu~lity o:f glas~ melt tend~ to deteriorate in p~].ae~ maklng furnace~ due to electrolytic decompo~ition of the melt under -the action of a current havine a.den~ity 10 mA/cm2 .
; According to another known technique~ corrosion protection is effected by means of electrodes i~ner~ed in a melt and current-conducting elements ~ecured in ~n inter-medi~te glazed coating made on the refractory material, these current-conducting elements being oonnected to the oppo3ite pole~ of a direc-t ourrent ~ource; the emf of the '`'`'' .
~L~365(3~
direct curren-t source being adju~ted ~o -that -the current den~ity at the surface of con-t~ct of the melt with the re~:ractory material would be les~ than 1 mAi~cm .
This solution of the problem likewise ~ails to ensure a substantial increase in the service life o~ the lining, because it slow~ down only electrolytic corrosion oi the working ~ur~ace o~ the refrac-tory in the location where it i~ brough-t in contact with the melt.
~ here is further kno~n a furnace conætruction which to some extent solves the problem of extending the service life of the refractory lining, which compri~es a bath lined with a refractory material and containing a qilicate melt, and current-conducting elementæ arranged inside the lining to e~it on the working surface thereof below and above the melt level -to be connec-ted, respectively, -to positive and negatiYe poles of a direot ourrent source.
hlæ arrangement ¢ompensateæ for the thermal emf be~ween v~rlou~ portio~s o* the worki~e surface of the re~ractory linin~.
'rherefore, currents pasæing alon~ the ~urface and : cauæing corrosion o~ the refraotory lining are reduced.
However, other causes of corroæion remain, while the 3ust described arrangement is not capable of combatting them to re~ult in a failure to attain a æufficient e~tension of the service life of the re~rac-tory lining.
The principle object of the invention i~ to provide a de~ign of the industrial furnace snd arrangemen-t of ~236~0~9 current-conducting element~ which woulcl be able to ensure a prolonged service life of the re-fractory lining as well as to increase the furnace capacity due to reducing repair works downtime.
The ob3ect is attained by that in a furnace compris-ing a bath lined with a refractory material and contain-ing a melt and having current-conducting elements arranged in the lining to exit on its working surface below and ahove the level of the melt, these current-conducting ele-ments being connected to opposi-te pole of a direct current source, according to the invention, there are provided addi-tional current-conducting elements arranged in the linin~ short of e~iting on its working surface and con-nected to the pole pieces o~ the direct current source o~
opposite polarity relative -to the connection of the our-rent-conducting elemeIlts of -the correspondln~ working surface.
Preferably, at least three ourrent-conduc-ting ele-rnents are disposed below the melt level, -two of these element~ e~iting on the working surface of -the lining a-t different hei~ht, whereas the third i~ interposed between these two short of e~iting on the ~vorkin~ surface of the lining.
~ or a more ef~ective protection from oorrosion it is preferable that substan-tially below the melt level the current-conducting elements exitin~ on the working surface o~ -the bath wall llning would be arranged at a dis-tance from the melt level and the bottom of the ba-th equal to ~2:3650~
between 0.1 and 0.2 the linin~ -thicknes~ 7 whercas the current-conduc-ting element failing to exi-t on -the working surface of the linin~ would be.spaced at equal distances from said elements~
The aforedescribed ernbodiment o~ the invention opti-mizes condi-tions for the protection of refractory lining from corrosion and extends the furnace lining service life~
The es~ence of -the invention resides in as follows.
~ urnace o~eration is accompanied by a substan-tial temperature difference between the working ~urface of the refractory lining and its inner body to result in a thermo-electromotive ~orce and, a~ a consequence, elsctric cur-rent. ~his current -tend~ to cause accelera-tion in electro-chemical corro~ion in the lining body, which in turn lead~
to structural defects in the thick boundary layers clo~e to the workin~ ~urface o~ the lining and a ~ubsequent los~
of ~trength -to a ~ubstan-tial depth of the linin~.
Re~earch has ~hown that the provision in the lining of additional current-conducting elements which do not exi-t on the working surface thereof a~d which are con~ect-ed to -the poles of the direct current ~ource of opposite polarit~ rela-tive to the connection of the current-con-ducting elements of the corre,sponding workin~ surface make -the bulk of the lining less prone to corrosiorl.
It has also been established that this i~ ~ccompanied by a le~s pronounced pene-tratio~ into the refrac-tory o~
~23651)~3 the melt, as well as of the products o~ ~lelting and fuel combustion to thereby hamper the course of changing the chemical an~ mineralogical composition of the refractory and slow down the rate o~ formation of the s-tructural zones in the liningO Structural defects also appear at a much slower rate. In view of -the foregoing, the refractory retain~ sufficien-t stren~th through a longer service life, spalling o~ the lining is prevented, and ~ining durability is thu.s improved.
~ he provision below the melt level of a-t least three current-conducting elements of which two exit on the work-ing sur~ace of the lining at different heigh-ts, and one is interposed between the first two short of exiting on the working ~urface of the lining make~ it possible to di~tribu-te the electric ~ield produced by an external source ~lon~ the hoight of the bath wall~ and thereby com-pletely protect the lining of the bath wall~ from oorro~
~ion throughout its height.
~ he po~itioning of the current-conductin~ elements exiting on the working sur~ace of the bath wall lining a-t a distance from the level of melt and bottom of the bath equal -to between 0~1 and 0,2 the thicknes~ of the lining, anA the arran~ement of -the curre~t-conducting element failing to exit on the working ~urface of the lining at an equal distance from the two firstmentioned elements ènables to produce such a field pattern,which ensures irl the best po~ible manner protection from corrosion o~ those parts of the bath walls which are most prone to corro~ion, gl 23~5~9 particularly the parts adjacent the upper and lower melt boundary where vigorous physical and ohemical processes take placeO ~niform protection of the bath wall lining at -the remaining height thereof is al~o ~ssured.
~ he proposed arrangement makes furnace refractory lining 1.5 to 2 times more dur~ble. Production capacity of the ~urnace is thus enhanoed due to e~tended operating oycle, and reduoed do~ntime required for relining. Another attendin~ advantage is that modification of furnaces in line with the features of the present ~nvention is in-e~pensi~e, because no structural remaking of the furnace associated with high capital costs is required. Also, repair expenditures are sub~ta-~tially reduced. One more advantage is operating ~implicity of the proposed design.
~ he invention will be more fully understood from a more detailed d2scription that follows taken in corljunc-tion with the accompanying dr~wln~s 7 in which:
~ ig. 1 i~ a oross-sectional view o~ an industrial gl~ss Inaking furnace provided with additional current-con-ducting elements, and a diagr~l showin~ connection of these elements to a current source; and ~ i~. 2 is sub~tantially the same as illustrated in ~ig. 1~ the difference being in that the current-conduot-in~ elements are located below the melt level so that -two of these element e~i-t on the working surface of the refractory lining, while the third is interposed between the first two.
i5~
With reference to ~igs. 1 and 2, a furnace accord-ing to the invention comprii~es a bath 1 defined by walls 2 and a hearth 3 of lined with i3 re~ractory material, a glass melt 4, wiallis 5 of the upper section of the ~urnace, and a roof 6 also lined wi-th a refractory material. The refractory linin~ of the roof 6 and walls 5 overlying the level of the molten glass includei~ current~conduct-ing elemen-ts 7 exiting on the working surface o~ the lining, and additional current-conducting elements 8 failing to exi-t on -the working su.rface of the lining.
In the lining Oe- the hearth 3 and wallis 2 of -the bath 1 below the molten glass level 4 there are provided current-conducting elements ?a exiting on the working isurface, and addi-tional current-conducting elementis 8a withou-t exit on the working surface, A ishown in ~ig. 2, in the lining of the hearth and w~ s of the.bath 1 below the level o~ the mol-ten glasis there are provided at least three curxent-conductin~ elemerlt~ two o-f these elements indicated at 7a exit on the work~n~ iYur~ce o~
the lining, whereas one additional current-conducting element 8a fails to exit on the worki~g surface of the lining and is interposed between these elements 7a.
The current-conducti~g elements 7a exiting on the working surface of the linin~ made on the walls 2 of the ba-th 1 a.re arranged at a distance fro~ the level o~ the melt 4 and the bottom 3 of the`ba-th 1 which makes 0.1 to 0.2 the lining -thickness, whereais the current-conductir _ 9 _ ,~ " i ~7~36S~9 elemen-t 8a not exiting on the working sur~ace of the lining is spaced at equal distance from the elernent~ 7a.
All the current-conducting elements are generally stainless steel pl~tes between 1.5 and 2.0 ~m in thick-ness; al-ternatively, these elements may be ~bricated from other known and available durable materials, such a~
platinum, molybden~n, and the like.
The proposed ~urnace design al~o includes a source 9 of direct current with a po~itive polarity terminal 10 and a negative polarity termin~1 11. ~he current-conduc-ting elements 7a and 8 are connected to the terminal 10~ whereas -the current-conducting elements 7 and 8a are wired to the terminal 11, wires 12 being u~ed for such a connection.
The fur~ace according to the invention operates ag f`ollows, The proce~s of making the gla~s rnelt 4 i~ accomp~nied by the ~ppearance of a -therrnal emf in the refractory li~-lng o~ th~ walls 2 and 5, bottom 3, and roo~ 6 of -the ~urnace between the working surEace o~ the lining and its body, this em~ being induced by virtue of a temperature dif~erence therebetween and al~o due to difference~ in the chemical composition thereof caused by i~pre~nation of the re~rac-tory lining with the melt and the gaseous melt products in the furnace atmosphere, as well a~ due to the structural differences between the surface and deeper layers of the lining. A thermal emf also tends to be induced between the working surface of the linin~ above , . , ~23~5~9 the level of the ~elt and below that level, this emf being caused pxima:rily by a difference in the chemical compo~i-tion Or the furnace products tending to lmpregnate the lining sur~ace~ in the~e area~ herewit~l, the ~urface of the wall~ 5 and roof 6 above -the level of the melt and the interior lining Gf the wall~ 2 below the melt level will be charged positively with respect to both the charge of the interior o~ -the walls 5 ana roo~ 6 above the melt level and ~he charg~ o~ the ~urface of -the walls 2 below the mel -t level. The pot en t i al differenc e amoun t ~ to between 0.7 and 1.0 V.
Subsequent to connecting all the current-conducting element~ 7, 7a, 8, and 8a to the terminals 10 and 11 o~
the direct current ~ource by mean~ of the connecting wires 11 as shown in ~i~s~ 1 and 2, a voltage of from 3.0 to 4.0 V i~ applie~ -to the current-conducting element~.
An electric ~ield induced thereby in the lining by the current~conducting element~ i~ op~osed -to -the thermal emf throughout the lining areas.
.
~hanks to that the current ~ource produce~ a volta~e , . , in exce~s of the magnitude of the thermal em~, a ~ ld cre~ted by the current-conducting elements is quite suf-~icient for reliably ~uppres~ing corrosion-inducing cur-rents de pite of the di~crete arrangement o~ -the current--conductint~ elements in the lining and a c~rtain voltage drop in the connecting wires, whereby damage o~ the re~rac-tory lining is delayed.
.
~36S~)9 In view of the foregoing, the proposed device offers substantial advantage~ over the prior art, since i-t enables to extend the service lif'e of the re~ractory lining of the ~urnace to thus make it more economically ef~ici.ent.
! 12 -. - .
FUl~ACE
'~his invention relates to the art of preventing a refractory furnace lining from wear by applying an elect-ric field. More particularly, it relates to industrial furnaces u~ed in metallurgy and glass production.
Major reaso~s for refractory lining wear are u3ually heat load~ and high-temperature corrosion induced b~ melts a~d gase~ accompanying the burning of a fuel, as well as by ~he liquid and gaseous melting products.
Heat loads exerted on the lining are di~tinguished by non-uniform heat ~luxes and temperature patterns, as well a~ by ~requent -temperature v~riation3, resul-ting in mecha-nic~l ~trains in the lining and eventually in ~pallin~
thereof.
Corro~ion affects the structure of the lining working ~urface in contact with the melt and furnace ga~eou~ at-mosphere to re~ult in deterioration o~ i-ts ~trength and in turn in a considerable a¢celeration o~ spalllne.
Du~ing furnace operation -the surface of the refractory material ba~ed on such heat-resi~ta~t metal oxides as ~1203, CaO, MgO, ZrO a~d the like is impregnated with various substance~, particularly molten metal~ and sla~ in melting furnaces, molten heat-transfer medium in hea-ting furnQces, and in mo~t cases with g~seous products. This gives rise to the formation o~ an area of complex chemical composition, which may h~ve the proper-tie~ of both semicon-du¢tors and solid electrolytes. ~he temperature of this . ~
~L23~S~
area in non-uniform at various points; that i~ ~ome areas are heated more than the others. In tu~n, -thi~
promotes the appearance of a thermoelectromotive ~orce (thermal em~), which induces an electric current in the lining to cause an excessive electrochemical corrosion of the refractory.
~ he magnitude and direction of this electromotive force depend on t~e chemical compo~ition of the refractory lining impreg~ated with the ~urnace produc-ts, and on the temperature difference. If the temperature difference is ne~ligeable, it can be con~i~ered that that E = ~ ~ T, wh~re E is the magnitude of the thermal emf between two pointa, ~ r is the temperature di~ferenoe between the~e points, and ~ i~ a constant eoefficient -takîng into account the compo~ition of the refrac-tory material. l~ormal-ly, the ~urnace operation i~ accomp~nied by a thermal emf of botweerl 0.5 and 2.0 V.
~ he n~ture and rate of elecSrochemical corrosion vary a~d depend o~ the conductivit~ of the area throu~h which the electric current pa~es. As a rule, both conduction by electrons and ionio co~duotion take place.
A multitude of techniques are employed for fighting Gorrosion of the furnace refractory lining.
; One such -technique involves immer~io~ in a melt bath o~ at least one electrode o~ a aurable material, wherea~
the zirconium~o~ide b~sed re~ractoriea to be protected are brought into contact with metal conductors for a continuous ~X3650~
em~ produced by an ex-ternal ~ource to ari~e between the~e conductors and the electrodes immersed in the bath, whereby an electric current ~low~ from -the electrode to the refractories to be corrosion-protected. ~he em~ is adjusted so as to provide an electrolytic current having a den~ity ~t the surface o~ the refractory on the order of 10 mA/cm2.
~ here~ore, corrosion is inhibited due to ionic exch~nge c~used by a difference between the chemic~l po-te:ntials o~ the molten sub~tance and the surface of the refractory.
Inherent in the above technique is a di~advantage re~iding in that it i~ applicable exclusively to re~rac-torie~ based on zirconium o~ide. In addition, it ~ails to provide for a substantial increase in the durability of the refractory lining, since i-t ac-t~ to defer only one rather than all kinds of corrosion. Another di~adva~tage i~ that the qu~lity o:f glas~ melt tend~ to deteriorate in p~].ae~ maklng furnace~ due to electrolytic decompo~ition of the melt under -the action of a current havine a.den~ity 10 mA/cm2 .
; According to another known technique~ corrosion protection is effected by means of electrodes i~ner~ed in a melt and current-conducting elements ~ecured in ~n inter-medi~te glazed coating made on the refractory material, these current-conducting elements being oonnected to the oppo3ite pole~ of a direc-t ourrent ~ource; the emf of the '`'`'' .
~L~365(3~
direct curren-t source being adju~ted ~o -that -the current den~ity at the surface of con-t~ct of the melt with the re~:ractory material would be les~ than 1 mAi~cm .
This solution of the problem likewise ~ails to ensure a substantial increase in the service life o~ the lining, because it slow~ down only electrolytic corrosion oi the working ~ur~ace o~ the refrac-tory in the location where it i~ brough-t in contact with the melt.
~ here is further kno~n a furnace conætruction which to some extent solves the problem of extending the service life of the refractory lining, which compri~es a bath lined with a refractory material and containing a qilicate melt, and current-conducting elementæ arranged inside the lining to e~it on the working surface thereof below and above the melt level -to be connec-ted, respectively, -to positive and negatiYe poles of a direot ourrent source.
hlæ arrangement ¢ompensateæ for the thermal emf be~ween v~rlou~ portio~s o* the worki~e surface of the re~ractory linin~.
'rherefore, currents pasæing alon~ the ~urface and : cauæing corrosion o~ the refraotory lining are reduced.
However, other causes of corroæion remain, while the 3ust described arrangement is not capable of combatting them to re~ult in a failure to attain a æufficient e~tension of the service life of the re~rac-tory lining.
The principle object of the invention i~ to provide a de~ign of the industrial furnace snd arrangemen-t of ~236~0~9 current-conducting element~ which woulcl be able to ensure a prolonged service life of the re-fractory lining as well as to increase the furnace capacity due to reducing repair works downtime.
The ob3ect is attained by that in a furnace compris-ing a bath lined with a refractory material and contain-ing a melt and having current-conducting elements arranged in the lining to exit on its working surface below and ahove the level of the melt, these current-conducting ele-ments being connected to opposi-te pole of a direct current source, according to the invention, there are provided addi-tional current-conducting elements arranged in the linin~ short of e~iting on its working surface and con-nected to the pole pieces o~ the direct current source o~
opposite polarity relative -to the connection of the our-rent-conducting elemeIlts of -the correspondln~ working surface.
Preferably, at least three ourrent-conduc-ting ele-rnents are disposed below the melt level, -two of these element~ e~iting on the working surface of -the lining a-t different hei~ht, whereas the third i~ interposed between these two short of e~iting on the ~vorkin~ surface of the lining.
~ or a more ef~ective protection from oorrosion it is preferable that substan-tially below the melt level the current-conducting elements exitin~ on the working surface o~ -the bath wall llning would be arranged at a dis-tance from the melt level and the bottom of the ba-th equal to ~2:3650~
between 0.1 and 0.2 the linin~ -thicknes~ 7 whercas the current-conduc-ting element failing to exi-t on -the working surface of the linin~ would be.spaced at equal distances from said elements~
The aforedescribed ernbodiment o~ the invention opti-mizes condi-tions for the protection of refractory lining from corrosion and extends the furnace lining service life~
The es~ence of -the invention resides in as follows.
~ urnace o~eration is accompanied by a substan-tial temperature difference between the working ~urface of the refractory lining and its inner body to result in a thermo-electromotive ~orce and, a~ a consequence, elsctric cur-rent. ~his current -tend~ to cause accelera-tion in electro-chemical corro~ion in the lining body, which in turn lead~
to structural defects in the thick boundary layers clo~e to the workin~ ~urface o~ the lining and a ~ubsequent los~
of ~trength -to a ~ubstan-tial depth of the linin~.
Re~earch has ~hown that the provision in the lining of additional current-conducting elements which do not exi-t on the working surface thereof a~d which are con~ect-ed to -the poles of the direct current ~ource of opposite polarit~ rela-tive to the connection of the current-con-ducting elements of the corre,sponding workin~ surface make -the bulk of the lining less prone to corrosiorl.
It has also been established that this i~ ~ccompanied by a le~s pronounced pene-tratio~ into the refrac-tory o~
~23651)~3 the melt, as well as of the products o~ ~lelting and fuel combustion to thereby hamper the course of changing the chemical an~ mineralogical composition of the refractory and slow down the rate o~ formation of the s-tructural zones in the liningO Structural defects also appear at a much slower rate. In view of -the foregoing, the refractory retain~ sufficien-t stren~th through a longer service life, spalling o~ the lining is prevented, and ~ining durability is thu.s improved.
~ he provision below the melt level of a-t least three current-conducting elements of which two exit on the work-ing sur~ace of the lining at different heigh-ts, and one is interposed between the first two short of exiting on the working ~urface of the lining make~ it possible to di~tribu-te the electric ~ield produced by an external source ~lon~ the hoight of the bath wall~ and thereby com-pletely protect the lining of the bath wall~ from oorro~
~ion throughout its height.
~ he po~itioning of the current-conductin~ elements exiting on the working sur~ace of the bath wall lining a-t a distance from the level of melt and bottom of the bath equal -to between 0~1 and 0,2 the thicknes~ of the lining, anA the arran~ement of -the curre~t-conducting element failing to exit on the working ~urface of the lining at an equal distance from the two firstmentioned elements ènables to produce such a field pattern,which ensures irl the best po~ible manner protection from corrosion o~ those parts of the bath walls which are most prone to corro~ion, gl 23~5~9 particularly the parts adjacent the upper and lower melt boundary where vigorous physical and ohemical processes take placeO ~niform protection of the bath wall lining at -the remaining height thereof is al~o ~ssured.
~ he proposed arrangement makes furnace refractory lining 1.5 to 2 times more dur~ble. Production capacity of the ~urnace is thus enhanoed due to e~tended operating oycle, and reduoed do~ntime required for relining. Another attendin~ advantage is that modification of furnaces in line with the features of the present ~nvention is in-e~pensi~e, because no structural remaking of the furnace associated with high capital costs is required. Also, repair expenditures are sub~ta-~tially reduced. One more advantage is operating ~implicity of the proposed design.
~ he invention will be more fully understood from a more detailed d2scription that follows taken in corljunc-tion with the accompanying dr~wln~s 7 in which:
~ ig. 1 i~ a oross-sectional view o~ an industrial gl~ss Inaking furnace provided with additional current-con-ducting elements, and a diagr~l showin~ connection of these elements to a current source; and ~ i~. 2 is sub~tantially the same as illustrated in ~ig. 1~ the difference being in that the current-conduot-in~ elements are located below the melt level so that -two of these element e~i-t on the working surface of the refractory lining, while the third is interposed between the first two.
i5~
With reference to ~igs. 1 and 2, a furnace accord-ing to the invention comprii~es a bath 1 defined by walls 2 and a hearth 3 of lined with i3 re~ractory material, a glass melt 4, wiallis 5 of the upper section of the ~urnace, and a roof 6 also lined wi-th a refractory material. The refractory linin~ of the roof 6 and walls 5 overlying the level of the molten glass includei~ current~conduct-ing elemen-ts 7 exiting on the working surface o~ the lining, and additional current-conducting elements 8 failing to exi-t on -the working su.rface of the lining.
In the lining Oe- the hearth 3 and wallis 2 of -the bath 1 below the molten glass level 4 there are provided current-conducting elements ?a exiting on the working isurface, and addi-tional current-conducting elementis 8a withou-t exit on the working surface, A ishown in ~ig. 2, in the lining of the hearth and w~ s of the.bath 1 below the level o~ the mol-ten glasis there are provided at least three curxent-conductin~ elemerlt~ two o-f these elements indicated at 7a exit on the work~n~ iYur~ce o~
the lining, whereas one additional current-conducting element 8a fails to exit on the worki~g surface of the lining and is interposed between these elements 7a.
The current-conducti~g elements 7a exiting on the working surface of the linin~ made on the walls 2 of the ba-th 1 a.re arranged at a distance fro~ the level o~ the melt 4 and the bottom 3 of the`ba-th 1 which makes 0.1 to 0.2 the lining -thickness, whereais the current-conductir _ 9 _ ,~ " i ~7~36S~9 elemen-t 8a not exiting on the working sur~ace of the lining is spaced at equal distance from the elernent~ 7a.
All the current-conducting elements are generally stainless steel pl~tes between 1.5 and 2.0 ~m in thick-ness; al-ternatively, these elements may be ~bricated from other known and available durable materials, such a~
platinum, molybden~n, and the like.
The proposed ~urnace design al~o includes a source 9 of direct current with a po~itive polarity terminal 10 and a negative polarity termin~1 11. ~he current-conduc-ting elements 7a and 8 are connected to the terminal 10~ whereas -the current-conducting elements 7 and 8a are wired to the terminal 11, wires 12 being u~ed for such a connection.
The fur~ace according to the invention operates ag f`ollows, The proce~s of making the gla~s rnelt 4 i~ accomp~nied by the ~ppearance of a -therrnal emf in the refractory li~-lng o~ th~ walls 2 and 5, bottom 3, and roo~ 6 of -the ~urnace between the working surEace o~ the lining and its body, this em~ being induced by virtue of a temperature dif~erence therebetween and al~o due to difference~ in the chemical composition thereof caused by i~pre~nation of the re~rac-tory lining with the melt and the gaseous melt products in the furnace atmosphere, as well a~ due to the structural differences between the surface and deeper layers of the lining. A thermal emf also tends to be induced between the working surface of the linin~ above , . , ~23~5~9 the level of the ~elt and below that level, this emf being caused pxima:rily by a difference in the chemical compo~i-tion Or the furnace products tending to lmpregnate the lining sur~ace~ in the~e area~ herewit~l, the ~urface of the wall~ 5 and roof 6 above -the level of the melt and the interior lining Gf the wall~ 2 below the melt level will be charged positively with respect to both the charge of the interior o~ -the walls 5 ana roo~ 6 above the melt level and ~he charg~ o~ the ~urface of -the walls 2 below the mel -t level. The pot en t i al differenc e amoun t ~ to between 0.7 and 1.0 V.
Subsequent to connecting all the current-conducting element~ 7, 7a, 8, and 8a to the terminals 10 and 11 o~
the direct current ~ource by mean~ of the connecting wires 11 as shown in ~i~s~ 1 and 2, a voltage of from 3.0 to 4.0 V i~ applie~ -to the current-conducting element~.
An electric ~ield induced thereby in the lining by the current~conducting element~ i~ op~osed -to -the thermal emf throughout the lining areas.
.
~hanks to that the current ~ource produce~ a volta~e , . , in exce~s of the magnitude of the thermal em~, a ~ ld cre~ted by the current-conducting elements is quite suf-~icient for reliably ~uppres~ing corrosion-inducing cur-rents de pite of the di~crete arrangement o~ -the current--conductint~ elements in the lining and a c~rtain voltage drop in the connecting wires, whereby damage o~ the re~rac-tory lining is delayed.
.
~36S~)9 In view of the foregoing, the proposed device offers substantial advantage~ over the prior art, since i-t enables to extend the service lif'e of the re~ractory lining of the ~urnace to thus make it more economically ef~ici.ent.
! 12 -. - .
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A furnace comprising:
a bath lined with a refractory material and con-taining a melt, main current-conducting elements arranged in said bath to exit on its working surface below and above the melt level, a direct current source to opposite terminals of which are connected said main current-con-ducting elements; additional current-conducting elements arranged in the refractory lining short of exiting on the working surface thereof; said additional current-conduct-ing elements being connected to said pole terminals of said direct current source of opposite polarity relative to the connection of said main current-conducting elements of the corresponding working surface.
a bath lined with a refractory material and con-taining a melt, main current-conducting elements arranged in said bath to exit on its working surface below and above the melt level, a direct current source to opposite terminals of which are connected said main current-con-ducting elements; additional current-conducting elements arranged in the refractory lining short of exiting on the working surface thereof; said additional current-conduct-ing elements being connected to said pole terminals of said direct current source of opposite polarity relative to the connection of said main current-conducting elements of the corresponding working surface.
2. A furnace as defined in claim 19 in which at least three current-conducting elements are disposed below the melt level, two of these current-conducting elements exiting on the working surface of the lining at different height, whereas the third is interposed between said two short of exiting on the working surface of the lining.
3. A furnace as defined in claim 2, in which the current-conducting elements exiting on the working surface of the bath wall lining are arranged at a distance of 0.1 to 0.2 the lining thickness from the melt level and the bottom of the bath, whereas the current conducting element which fails to exit on the working surface of the lining is spaced at equal distances from said elements.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000464674A CA1236509A (en) | 1984-10-03 | 1984-10-03 | Furnace |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000464674A CA1236509A (en) | 1984-10-03 | 1984-10-03 | Furnace |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1236509A true CA1236509A (en) | 1988-05-10 |
Family
ID=4128839
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000464674A Expired CA1236509A (en) | 1984-10-03 | 1984-10-03 | Furnace |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1236509A (en) |
-
1984
- 1984-10-03 CA CA000464674A patent/CA1236509A/en not_active Expired
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