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COOLING ELEMENT FOR SHAFT FURNACES
The invention pertains to a cooling element for shaft
~=urnaces, especially blast furnaces, with an area through which a
coolant, preferably water, flows as the result of the arrangement
of at least one internal coolant-carrying r_hannel, which leads to
coolant feed and discharge pipes cannec~ed to the cooling
element, the cooling elemenr_ also havirAg edge areas.
Cool.ir_g elements of -..his type, also known as "staves", serve
to cool she walls of blast-_ :~.irnaces . They are a sual.ly installed
between the steel furnace jacket an<~ the furnace lining and are
provided ~Nith refractory naterial on the side facing the interior
of the furnace.
Cooling elements are known in ~f~h,~ch the cooling channels are
formed by pipes, casually nw:acie of stee-~ , whi~~h are cast into a
matrix{ of cast iron. 'The co-oling channels passing through r_he
cc>oling element are usually ,~rvanged ver.tica-ply with respect to
c'~.e longitudinal axis of the base be>dy. 'these plates can also
ccr_sist of cast copper instead of cast .iron. In addition, forged
or rolled cooling plates cr ~.o~:~per cr low--alloy copper are also
known, the cooling channel:, of which a.re vertically oriented
blind bores, which are introduced by deep mechanical drilling or
milling. Finally, it is also known a:..hat a coolir_g element can be
nr~~duced from one or rr;ore ~~;.~:=~=ruled or .rolled profiled sections,
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the interiors of which are provided with coolant channels.
A feature essential~..y common to all of the known staves is
=hat they have an area through which a caoiant flows as the
==esult of the arrangement of cooling channels, which lead no
coolant feed and discharc:~e pipes passing through the wall of the
blast furnace, the stave~:~ also having edge areas, which extend
essentia.tly beyond the pipes. These edge areas are not cooled as
:_ntensively, of course, as the area of the staves through vahich
t:he cooling channels pass. 'The reason for the ,mess intensive
cooling of the edge areas is the disproportionately large
distance between the coolant-carrying area and the corners or
edges of the staves, that is, the end areas. The heat which
accumulates there must be ~_ransport.ed by conduction to the cross
section through which the coolant f:ows, This leads to higher
temperatures at the corne-~s and edges r_han in the other areas of
the stave and th~.::s to ther_ma~. st:res~es, to overheating, and, to
premature wear. Staves of <:.fist: iron. in particular suffer losses
of material especial~_y at t~:.fm cc>rners :end edges, as a result of
which ultimately the adja~_w.nt:. areas of the steel jacket around
the blast furnace arc= no ~or_ger adequately protected. It thus
becomes necessary to repl:~cF.- the staves ir~ question. In the case
of copper staves, the samfe basic prc:biems also occur, but because
of the much higher thermal. c~onducti~~i~y ef copper, they occur
later and to a less prono~:nced degree.
For geometric and mar=ui:acvuring reasons, the cooling pipes
cannot be moved as far as or.e :night w~.sh ~nco the edge areas of
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t:he staves to improve tht: .r.oo:Lirg effect. So-called
"compensators", furthermc:~re, are i~,sta~:.led on the outside surface
of the steel jacket of t:~,e furnace, which have t:~e job of
allowing the cooling pipe's to pass in a gas-tight manner through
t:he steel jacket. Because ~~f their geometric dimensions, these
compensators require that. the centers of the cooling pipes must
~~e maintained at certain vertical and horizontal distances from
each other. These d.istan:E=s must also be maintained so that the
steel jacket of the furna~:?e ~s not weakened too much, whicra could
be the case if the holes were too closely spaced in their rows.
In the case of staves with east--in pipes, furthermore, the
outside diameter and wall thickness of the pipes limit the degree
to which they can be bent . wh;ch means that it i:~ impossible to
bend them into a shape wh-~c-h could allow them to pass through the
edge area.
The problem of i.nade~.;.ate cooai.ng at the corners and edges
of the cool ing elements i:~ solved b~,~ r.. he cool=ing plate described
in EP 94 115 821, in that i~s edge areas are provided with bores,
the cross section of which :~s smaller than. tat of the cooling
channels proper. Considevecoverall, an independent cooling
system with its c>wn coolar_t inlets and outlets is proposed, this
system being obtained by r_he use of vertical and horizontal bores
in the edge area. Also provided are the required pipe
connectors, which extend through the blast 'urrace wall.
The vr~~~enticn is based on the task of creating a cooling
e7_ement of the basic type in questic:n w~?i:c~~ offers improved
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DE 33 13 998 A1 discloses a coo-~ing elate for metallurgical
furnaces and a method c>f producing it. 'his cooling plate
consisr_s of a cast matE:r.i.a:l, in vahich ~:he coolant channe?_s are
formed by steel pipes. i'o provide a cool~.ng element with an
unjacketed steel pipe with satisfacr_c~ry heat tv~ar_sfer, a bore
extending from a surface on the narrow side of the casting into
the ,interior of the cas ~.ing i_s proi~:i_ded, such ',.:hat a steel pipe
in cress connection with: the wall of the bore is inserted in the
bore. Since ivy is difficwl.t to insart a pipe with a curved elbow
section into a vertical bore, and the relatively large openings
at the head anc~ enca reg:i.c,~n of the plates must fee sealed with
refractory material, it is proposed ~:zat ~=le feed and discharge
of the coolant be c:ombiraed on one side of ~he cooling plate. The
steel pipe is constructed as a doub-'.~e-jac~:et pipe, which .is
closed by a ba~:e at: its lower end. The coolant flows through the
outer annular region into the cooling element and back through
the inner pipe.
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cooling v~n the end areas, that. is, at tote edges.
To accomplish this task, a cooling element with the features
c>f Claim 1 is proposed. Advar:tageo::s elaborations are disc:losed
i.n the subclaims.
In contrast to the st<~te ~:~f the art, the proposed coo7_ing
system is not an independent cooling sy:~tem with its own pipe
cor~nectors -- which weaken the wall of the blast furnace -- but
rather a modificat10T1 Of the r_ooianr_ f eed system ac~~ording to
which the cooling channels passing through the base body are
extended all the way to the edge areas, including the corner
areas, if desire<~. In tre az.~ea whe a the coolant-. leaves tr:e
stave, the cross section :r the charm ~~? e:<a.ending through the
edge area is comparativel-,r l arger a::d is provided with a
(coolant) guide element, ao ,..hat thc, ~ooi.ant, coming from the
base body, flows into the edge area, reverses direction, and
flows back essentially in tie «ppos-ite Direction to the opening
of the pipe. At the end .~ri~.~re the cooiar~ ent=er.~> the stave, the
c~~olant is guided first t~:-> -.he edge a,:~ea ar_d flocns from there
into the base body trrough .she cooling channel . It i s
a~3vantageous here foz: the c~.wcss secr-ion cf ;:he cc:~oli.ng section to
bE~ doubled, so that t:~~E ac~tv,,al cross «ections of the two parts of
the channel in the coolinc; section 'r~hich carry the coolant in
opposite directions will '..>~~ the samF~ as that of the main cooling
channel in the base body. a.s a resu,~t= of this measure, a
homogeneous flow ~~relocity is obtained ~.vithin the cooling system.
The cooling effect. ors the f=dge a~.~co-r~~er areas of the stave
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i.s therefore improved wit:ho~at the need r_o make any change i_n the
spacing of the cooling pipe pass-throughs, i.e., in the spacing
of the pipes passing throu<~h the steel jacket of the furnace,
this being the spacing whi;-h is determined by th~~ compensat:ors.
Overall, therefore, the goal is achieved that the coolant can be
conducted right to the edges of the staves. The distance which
.till remains between the a real through which the cooling water
can flow and those through which it cannot flow is r_hus
significantly reduced, na:me~r, to t.',~e same value which is present
in the regular part of the cooling ~~lemer.t: and which is
sufficient for adequate cc~~r_>linc~.
As an especially pre~~~rred embud_iment, it is proposed that
the edge area of the cooling ewemer_t ae designed as a separate
endpiece, the coolin~:~ cha!zrrel sectiwr_c, c>f which are provided with
guide elements. The separate endpiece is attached to the base
body, which carries t=he it:cmnal co<:~lvng charnels. The endpiece
can be manufactu_=ed ass a ~ir:yri_e uni.~ y__ t~.e form of a casting or
forging, for example, or _~.:. car. consi~at of several pieces which
are welded together. The er:cipiece _~s preferably designed so that
it already has an appropri_a.te bore nor receit,Ting the opening of
the coolant feed or ciiscr.~ar~:,e pipe which passes in each case
through the wall of r_:re s~:a.': ~ fu.rnare .
In the case of <~ sta~.Te~ with a x:aa:.~e body with several
vertical cooling channels; t~l-:e endp~ece which is provided should
have the same nur:lber of c:_>c iin~ 5ectie~ns as there are internal
v?r~ical cooling channels . ~r: cane va::~e cf a sta~~~e assembled from
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several profiled section.<:, the number of endpieces could
<:orrespond to tr.e number of profiled sections.
A preferred embodime:~nt o.f the cooling element according to
the invention is describf:~d in the ~ol.~owing:
-- Figure 1 shows a :aide view of parts of two cooling
elements with endpieces ~~.s propose<~ according' to the invention,
c>ne element being instal:~ed above the other;
-- Figure 2 shows a <,riew of the cooling elements according
t.o Figure 1 from the perspective of the steel jacket around the
furnace;
-- Figure 3 shows a :~:irae view ~:~f parts of two cooling
elements according to the state of ;=he <~_~-r , one i nstall ed above
the other; and
-- F figure 4 shows a v~~:ie~,~ of the cool.::.ng elements according
to Figure 3 from the persp~~ct=i<re of tine steel ja~:ket of the
furnace.
Ffigure 1 shows .parts ~::~' two staves , 2. ~a pipe 3 for the
discharge of coolant is c~:r,_:iect:ed to the t:c~p end of the lower
stave 1, whereas a pipe 4 ~:t:>r suppl-~i:ng coolant ~s connected to
the bottom end of tree upp~:a~- octave v . The pipes 3 , 4 themsel yes
pass through opening: 6, ' v,_n t:he f~.~r:~ace wall
Each of the sta~,~es 1, ', compr~:.ses a base body ~3 with
v?rtical cooling charnels ~~~ . i'he s~:ayes c~cns:ist of copper or of
a low-alloy copper. On t'ne =~i.cie fac:i:~g the interior of the
fwrnace, the staves 1., a ~m==' provicAed with webs and grooves 10,
11 to accept refractory m;;:~t..-~z-i:al. ~~ ar:dpiece 1~a;~ proposed by
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t:he invention is welded t o the top er..d of the base body 8 of the
stave 1. This endpiece r.as a channel section ~y3 forming an
extension: of the associated vertical cooling channel 9 or several
channel sections forming e:tension:~ of w-:~e several cooling
<:hannels in the base body,, only one ef wh.ic:h cars be seen in the
cross-sectional view shown. The cross secr_ion of the channel
;section 13 is larger than t:'~:at: of t:he ~;~er.-_ :cal cooling channel 9
and is divided over part c~f its length by a guide element '~4. In
t:he embodiment shown, the guide element L~ forms a direct
E~~aension of the side 15 o:E the channel whwch can be seen in the
base body, i.e., the side Facing t:~e steel packet of the furnace.
When: castings are us ecA, an appro_r.~r:_ate bore i s introduced
into the separate endpiecc= :~t the level c>L the pipe 3 , so that
the endpi.eces ca:n be connected to the pipes passing through the
blast furnace wall. Where ~ ~.ve~~ded cons t:ruction is used, Clue
endpiece can be :Trade of se~.;era.i pats, .Jrhich are then welded
together.
The way in which the wat=er flcms through the lower stave 1
and its ~.op part 12 is de:acr=_bed beloeN ~~nd illu~~i:rated with the
help of arrows. The cooling water ;~.s gui.cied through the proposed
endpiece 1 3 in such a way t: Y:at it !. v_.rst f:~.ows up all the wa.y to
the very edge of the cool~r~g elemer.'~ . Then, after reversir:.g
direction by 180'' , i t~ f lo.,~=~ a shor'= distance in the direction
opposite its original flov,v direction end then is redirectee.
again, th-_s time by '~a0'~, ..:~n:~> the ~:~~p~~ ? and ~hu:~ passes tr:.rough
the pipe 3 and an elbow f !:zc:t shown, m~~rela> suggested by a broken
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1. ine ) to the pipe 4 o f trv,e s rave 2 loc_a wed on top . Af ter t:he
cooling water has flowed th:ros_igh the uppermost stave, it is sent
into the coolant circuit of the blast f:~irnace.
The pipes 3, 4 ~hemsel~,res are surrounded by compensators 16,
17, which are necessary to ensure a gas--right seal of the pipes.
I:t is evident that optima:L cooling of the edge areas of the
cooling elements is achieved in spite o~ the spacing of the pipes
3, 4 necessitated by the compensators i5; 1'~.
The endpieces are preferably c~rovidecwith the pipes 3
before said endpieces are i.~:~t.alled.
It i.s not absolutely r:ecessary for both the top and bottom
ends of each stave to be r~;p:~a.ced ~.~;~~t: ~:r_ endpiec~e <~ccordin.g to
the invention with its mo::~.i~:.ed ~.aat~r channel . ?ve:: if the
modified ~Nater c:~annel is p~-ov,~cied at onl~,~ one e:ld (as s:~own
here) , t'~_e cooli~~,.g capacit_1~ is increased ..n the edge areas of
both adjoi ning s raves . I ~~ ~~.s arivar_~ageous for a stave to be
provided with a separate ~~nlpiec.e a: only ore er~:?. P.ithough such
an endpiece will be sponger t::nan wound be t:ha case if two
endpieces were u:~ed, that ..~>, one a-~ ~~he t.op and one at the
bottom, it offer: economi:~ ac~vantag~=s 1r. terms ~:i- manufacturing.
Figure 2 shows flow t_~e staves ar~= instal_Led on t':ze furnace
wall when the staves in qv.:e~st:ion hate er:dpi eces only at their top
ends. The staves 1, 2 shc:,wn here are assembled f=rom extruded or
roll ed sections, which ar~:3 ~.~~ce1_ded :~,ogrtt::er ar. thE> webs extending
al ong their long edges (sE>_e~ the de shed li~~e) . As indicated by
tae dash-dot line of the vvE.c..~ '~9, each. section i:_> ~,aelded at the
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top end to an endpiece 12 wvth the jvat~er. flow system according to
the invention. '~'he distance between the water feed pipes and the
seam 18 between the two sY.~~c:ked sta~"~es " , ~ is different from
teat between the water discharge pipes ar:d the seam. The seam is
thus not equidistant betwf~en the pipes ;see Figure 4).
The distanc~=s A and %?' in. Figure 2 are intended to show how,
as a result. of t;~:e water-c~oo'~ed endpiece 1~ with its flow-guiding
element 14, the czistance between the area through which cooling
water flows and v~he outer czdges of the staves is reduced,
resulting in an :impr~,>ved ,:gaoling action in the corners and edges.
It should bf=_ mention.:~r.~ that an endpiece attached to the top
end offers the advantage ~:~_: prov:iding a faxed point by which the
cooling element can be huang i_n place. Attac:~:ing the endpiece to
the bottom end o~ the cooLi.~Zg eiemer~t, however, offers the
advantage of reducing the darvger of the formation of_ air or vapor
spaces, the insulatir:g of :e~a~t ~7f w't::-~cco~~lu :interfere with good
cooling.
For comparison, Figu_:-e ? shows t~,'1e Water flow system of the
previous,~y known staves . T'he parts o E these coo~_irg elements
which are the same as thoae in Figure 1 rave been given the same
referer_ce numbers. The st:avres 20, «1 showr_ here are provided
with cast-in pipes 2a., ~~ as c.ooiing channels; w-rich are guided
by means of suitable shie..d. pipes ?4, 25 through appropriate
openings ~, 7 in r_he furn~~ce wall 5. The flow of: cooling water
between t:~e two :stave's is ~:yain i.nci~cated by a broker. line. It
i~ et.T:ider:t that, in compae:.5on ~,vlt~~: t~~ze cooling ~,lements proposed
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in accordance with the in;rent~ion, much charger edge areas 2E~, 27
a.re not cooled, which are therefore subject. to greater wear. For
comparison with Figure 2, ~~-~gure 4 shows a view of .stacked
cooling elements 20, 21 w~~:h vertical cooling channels 22, 23
according to the state of =ne art. In this prev_;.ously
conventional stave arrangement, the seam between two staves.
arranged vertically one abo~.re t=he ot-_her along the furnace wall is
basically the same distar~:~e away fr~:~m the two sets of cooling
channels and is therefore i.n tr:e centF~r between the associated
edge areas.
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