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Патент USA US2509856

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May 30, 1950
Filed April` 18 , 1946
5 Sheets-Sheet l
[email protected]
M „déb/2b
May 30, 1950
Filed April 18 , 1946
5 Sheets-«Sheet 2
May 30, 1950
Filed April 18, 1946
5 Sheets-Sheet 3
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May 30, 1950
Filed April 18, 1946
5 Sheets-Sheet 4
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Patented May 30, 1950
Emil Blaha, Cheltenham, Pa., assignor to Selas
Corporation of America, Philadelphia, Pa., a
corporation of Pennsylvania
Application April 18, 1946, Serial No, 663,158
18 Claims. (Cl. :Z5-142)
My invention relates to heating apparatus,
such a rate that the chamber atmosphere is
substantially free of objectionable and undesir
such as furnaces, kilns, and ovens, for example.
While the principles of the invention may be
able components. Thus, in practicing the inven
employed for a Variety of heating purposes,
tion to produce glazed or glass-like surfaces on
both industrial and otherwise, the improvements Ul articles, the heated products of combustion may
disclosed herein are especially useful in those
be withdrawn exteriorly of the chamber at such
heating applications in which consideration must
a rate from the combustion vicinities that the
be given to the character of the atmosphere en
chamber atmosphere is impoverished in sulphur
veloping the Work being heated, especially the
impurities to such a degree that the glazed or
presence of objectionable and undesirable con 10 glass-like surfaces produced are smooth and lus
stituents in the gases forming such Work en
0 trous and free of surface defects.
veloping atmosphere.
By effecting combustion of the gas mixture at
In view of the fact that the character of the
vicinities or zones adjacent to heat radiating
atmosphere enveloping the Work often is an
regions to heat such regions to incandescence,
important factor in many heating operations 15 such combustion vicinities or zones being in open
it has usually been the practice in such cases,
communication With the heating chamber, ra
when a combustible gas mixture is utilized as a
diant heat is projected from the regions Without
source of heat, to employ internally fired heat
the necessity of shielding the work or goods from
radiating muffles or tubes to keep the work or
the combustion zones by a heat transfer Wall
goods out of physical contact with the high temp
erature heating gases consisting of heated prod
20 or barrier like a muíîle. In this Way radiant heat
transfer may be accomplished at the highest
ucts of combustion. In this Way the heating
possible temperature from the heat radiating re
chamber is fired to an elevated temperature by
gions which are heated to a high incandescent
heat radiated from the exterior surfaces of the
condition and openly exposed to the heating
muiiles, and a gaseous atmosphere is provided 25 chamber at the surfaces adjacent to which burn
which is of such a character that it will con
ing of the gas mixture is accomplished.
tribute to produce the desired end result in the
In the embodiment of the invention disclosed
goods or Work being fired.
herein the heated gases generated and developed
Such heating practices have been followed, for
at the combustion zones or vicinities are With
example, in the firing of articles to produce glazed 30 drawn and diverted therefrom, without becom
or glass-like surfaces, as in the glost firing of
ceramic Ware and in vitreous enamelling. This
ing an active component of the chamber atmos
phere, by producing a suction effect adjacent to
is so because the high temperature heated prod
the combustion vicinities. Such suction effect
ucts of combustion usually contain harmful con
may be produced by an exhaust blower to cause
stituents, such as sulphur dioxide and sulphuric 35 withdrawal of the high temperature heated gases
acid fumes, for example, which adversely affect
exteriorly of the heating chamber through a path
the glazed surfaces produced on articles when
of ñow which is in heat exchange relation with
such heated gases freely circulate in the at
a Wall of the heating chamber. To promote fur
mosphere enveloping the Work.
ther the radiant heating of Work in the heating
In accordance With the present invention, it 40 chamber, the path of ñow through which the di
is proposed to heat Work to high temperatures
verted heated gases pass exteriorly of the heat
in heating chambers by radiant heat in such a
ing chamber may be formed of refractory ma«
manner that the character of the atmosphere
terial which is heated to incandescense and from
enveloping the Work may be accurately deter
the outer surfaces of which heat is radiated to
mined While projecting such radiant heat from 45 the interior of the heating chamber.
a plurality of heat radiating regions which are
The suction effect produced adjacent to the
heated to incandescense by a high temperature
combustion vicinities may be adjusted to effect
gaseous heat producing medium exposed to the
withdrawal of the heated gases from the vicini
chamber atmosphere. I accomplish this by With
ties at such a rate that heated gases can pass
drawing exteriorly of the heating chamber the 50 substantially by diffusion only from the combus
gaseous heat producing medium before such med
tion vicinities into the chamber atmosphere. Un
ium can pass into the heating chamber and be
der such conditions the gases at the boundaries
come an active component of the chamber at~
or interfaces between the heated gases formed at
the combustion vicinities and the chamber at
In order to produce high radiant heating temp~
eratures, the heat radiating regions are prefer
ably heated to incandescence by combustion of
r mosphere may be maintained practically quies
In practicing the invention the pressure‘firr the»
heating chamber may be slightly below tlfle=pres~>
sure of the surroundings and negative due to-y
communication with the heating chamber. The 60 the suction effect produced adjacent to the vicini-,-heated gases generated and developed at the com
ties at which combustion is accomplished. Such»
a combustible gas mixture effected at vicinities
or zones adjacent to such regions and in open
bustion vicinities or zones adjacent to the heat
radiating regions may be Withdrawn therefrom at
suction effect may be utilized to draw into the
heating chamber an essential gas which con
tributes to the end result desired when rlring
Work at high; temperatures. In the ñring of
articles to produce glazed or glass-like surfaces
thereon, for example, the negative pressure of
therefore embodied in the high temperature fir
ing zone;
Fig. 7 is an enlarged front View of a refractory
sential air into the chamber which purges the
gases in the chamber and contributesv to the
shape, partly broken away and in section, to
illustrate details of the burners embodied in the
high temperature firing zone;
Fig. S'is an exploded perspective View of the
ing gives up heat to essentialair in thecooling
clearly the final and last portioniof the cooling;v
the heating chamber may be utilized to draw'es
refractory shape of Fig. 7;
production of high quality glazed surfaces onY
'Fig 9 is an enlarged transverse vertical sec
tionalvievv, taken at line ël-S of Fig. 1, to illus
Further, in a continuous tunnel type furnace
trate the preheating zone more clearly;
or kiln having preheating and cooling zones a-t
Fig. l0 is an enlarged transverse vertical sec
the opposite ends of a high temperature firing
tional view, taken at line IQ--lßgoi Fig, 1A,_ t0 il’
zone embodying the invention, theessential air
lustrate details of iirst and second portions'of.:
may be drawn into the high temperaturezone
through the cooling- zone into which thework 15 the cooling zone of the continuoustunnel kiln;
Fig. 1l is an enlarged vertical sectional View.v
passesafter being ñred to the desiredhigh tem
taken-at line ll-H of Fig. 1A, to..illustrate more.
perature. l'n this way, theheatedworkincool
zone, and suchpreheated air. is then introduced.
Fig. 12 is a horizontal plan View of the con
into the nring zone to effectpurging of the gases 20
tinuous tunnel kiln of Figs. 1 to 11 and controlA
revisions for the kiln; and.
Due to the suction> effect produced adjacent to
Fig. 13 is a View diagrammatically illustrating
the vicinities at. which combustion. is accom.
the operating conditions existing; at the combus
plished,.there. will always bea tendency. for gases
of the chamberv atmosphere to be drawn eXte 25 tion vicinities adjacent to the refractory lined
riorly of the kiln or furnace along with the di
verted heated products of combustion .before such
heatedY products can become an active. compo
heat radiating regions distributed-along the ,high`
temperature firing zone.
In the drawings the instant inventionhas been.
shown in connection with a continuous tunnel
nent of the furnace atmosphere. Suitable control.
provisions may be providedto. control thein. 30 kiln lil through which goods or wares may be.
moved successively through a preheating zoneY
ñow ofv essential air into> the heatingk chamber,
or section I5, a high temperature firing zone-or
the rate of Withdrawal of the heated products of
combustion, and the pressure and rate> at which
section I l5 and a cooling zone or` sectionv l1.
is to be understood that the kiln I4=is only il
the combustible gasV mixture issupplied tothe
lustrative of one manner of practicing the in
vicinities at which combustion is accomplished.> 35 vention
for producing glazed or glass-like sur
Some or all of these variable factors may be con
faces on articles, and that the improvements dis
trolled, for example, responsive to a temperature
closed herein may be embodied in other forms
condition affected by the temperature maintained
of heating apparatus.
in the heating chamber.
40 VThe goods or wares to betreated are loaded'on>
rï‘he novel features which I believe to be char
kiln cars le, as shown in Figs. 3, 9.,_ 10 .and 11,
acteristic of my inventionare set forthwith par
which are moved slowly through the kiln chamber,
ticularity in the claims. The invention, both
on a track i9. Each kiln car laincludes a super
as to organization and method, together With
structure providing spaced apart. transverse pas
the objects and advantages thereof, will be better tvs Si sages 2û`at the underside cf a platformîl upon`
understood by reference to the follow-ing descrip
which the goods or wares, diagrammatically4 in
tion taken in connection with the accompany
dicated by the dotted line 22, are loadedin any»
ing drawings, of which:
Figs. 1 and 2 are longitudinal horizontal and
vertical sectional views, respectively, illustrating
more or less diagrammatically a preheating zone
and a portion of an intermediate high tempera
ture firing zone of a continuous tunnel kiln em
foodying the invention;
conventional manner.
A refractory, body portion of eachcar I8, which;
is carried by a metallic underframe, extends`
through an opening orslot> formed inthe bottom
wall ofthe kiln chamber. In this way narrow
gaps 23 are formed between the sides of the re
fractory' bcdy portions of the cars I8 andthe
Figs. 1A and 2A are longitudinal horizontal 55 side walls of the slot, the lower ends orjeachare
and vertical sectional views, respectively, dia
closed and sealed- at Zíi by flanges whichextend
grammatically illustrating another portion of the
downwardly frcm the, sides of the4 cars I.8~int0„
intermediate high temperature firing zone and
troughs adapted to contain sander likematerial.4
cooling zone of the kiln shown in Figs. 1 and 2;
Duringoperationof the kiln iii, the car-s I8 mov
Fig. 3 is an enlarged transverse vertical sec 60 ing through the kiln chamber are4 in abuttingre
tional view, taken at line 3_3 of Fig. 1, to illus
lation and the gaps Zï'sare effectively sealedat the
trate the high temperature firing zone more
lower ends thereof longitudinally of the` kiln,` as
just explained, so` as to minimize leakage of. air
Fig. 4 is an enlarged fragmentary transverse
into the kiln chamber.
vertical sectional View, taken at line 6_4 of Fig.
After the goods or wares to be treated are
5, to illustrate details of the high temperature
loaded on the cars i8, such cars are moved in suc
firing zone;
cession onto a transfer track 25, as best shown> in
Fig. 5 is an enlarged fragmentary longitudinal
Fig. l, on which the cars .pass into a side entranceV
sectional view, taken at line 5~5 of Fig. 1, to il
vestibule 2S having a normally closedslidingdoor
lustrate more clearly the side walls of adjacent 70 2l’. The vestibule 2B is located at the inlet endj
portions of the preheating andV high tempera
of the preheating zone i 5, and vestibule propeller,
ture firing zone, respectively;
mechanism '2i-l of any Well known type,> having a
Fig. 6 is an enlarged fragmentary horizontal
reciprocatory pusher member 29, may be provided Y
sectional view, taken at line iî-ö of Fig. 3, to
to move the cars £8 slowly through the kiln cham,-Y
illustrate more clearly the burners and iiues 75 ber. As shown in Fig. 1A, the cars liì‘discharged’
from the cooling zone l'í of the kiln chamber pass
The gas mixture introduced into the spaces or
into an exit vestibule 3l] from which the cars are
cavities 4l is subjected to the intense radiant heat
moved through a normally closed sliding door 3|
of the inner wall surfaces 54, so that substan
tially complete burning of the gas mixture may
onto a transfer track 32.
’I‘he sides of the kiln I4 are provided with suit
be accomplished in the spaces or cavities before
the heated gases pass from the open ends of the
able supporting framework 33 connected at the
spaces 4l. By providing the radiant heaters 45
upper ends by cross rods 34. The framework 33
extends the full length of the kiln and includes
metallic side walls 35 forming an outer shell for
the kiln i4. As best shown in Fig. 3, the refrac
a large fraction of the heat developed and gen
erated in the spaces 4| is converted to radiant
heat which is projected from the highly incan
descent wall surfaces 54 into the interior of the
tory kiln structure providing the high tempera
high temperature firing‘zone i6 to effect heating
ture ñring zone or section l5, which is disposed
within the framework 33 and outer metallic side
walls 35, includes spaced apart side walls 36, a
roof 3l, and a bottom 38 having the slot or open
of the goods or wares passing therethrough on
the cars i8.
The heated gases generated and developed at
the vicinities of the radiant heaters All pass into
ing therein through which the refractory body
portions of the cars i3 project, as previously
spaced apart vertical ñues 55 in the refractory
side walls 36, as will be explained more fully here
inafter. As shown in Fig. 5, the lower ends of the
vertical ñues 55 communicate with horizontal
ñues 56 provided in the firing zone at the bottom
parts of the refractory side walls 36. The ends of
the horizontal flues 56 terminating at the junc
In the refractory side walls 36 of the high tem
perature firing zone or section I 6 are mounted or l
incorporated gas-fired radiant heaters or burners
4U each having a cavity 4! at an inner face there
of opening into the kiln chamber. Each radiant
heater comprises a molded block 42 of ceramic
material having a central passage within which is
disposed a tube or sleeve 43 of refractory material.
As best shown in Figs. 3 and 6, the tubes or sleeves
43 extend rearwardly from the block 42 through
wells or openings 44 formed in the outer portions
of the refractory side walls 36. The extreme
outer ends of the tubes 43 may be connected by
ture of the firing zone I6 and cooling zone il are
closed, and the opposite ends terminating at the
juncture of the firing zone I5 and preheating zone
l5 communicate with the horizontal transverse
passages 5l formed in the bottom parts of a
pilaster 58.
As shown in Fig. 5, the lower ends of ver
tical íiues 53, which are offset laterally with re
spect to the horizontal flues 55 in the firing zonet
suitable flexible connections to apertured brackets
i8, communicate with the transverse passages
45 ñxed to the casing 35, as seen in Fig. 3. The
5l. Each side of the refractory kiln structure
tubes or sleeves 553 may also be spring-biased at
at the pilaster 58 is formed with openings or pas
the brackets in any suitable manner (not shown),
sages [email protected] at different levels which communicate
so as to cause the rear enlarged portion of each
with the vertical iiues 5€ and through which
tube to ñt snugly in position at the rear face of
heated gases may flow into horizontal heat trans
the block 42 with which it is associated.
fer flues el' extending lengthwise of the preheat
The heater tubes 43 are connected by pipes 46
to short horizontal manifolds 47 which in turn 40 ing zone i5 at each side wall of the kiln chamber
from the pilaster 58 to the entrance vestibule 26.
are connected by conduits 43 to larger vertically
horizontal flues 6i extending lengthwise of
disposed headers 49. The combustible gas mix
the preheating zone l5 and into which the heated
ture is delivered to the headers ¿i9 from a suitable
gases pass through the openings G0 from the
source of supply in any desired manner. In the
vertical iiues 53 are disposed one above the other
conduits 48 are connected manually operable
in the refractory side walls of the kiln, as shown
Valves 5D to control the pressure and rate at
in Fig. 9.
which the gas mixture is supplied to each horizon
The horizontal ñues 6l comprise a plurality of
tal manifold 42, and in the pipe connectionsI 45
rows of refractory shapes or tiles 62 in abutting
are provided manually operable valves 5l for indi
relation and secured together, as by a high-tem
vidually controlling the support of the gas mix
ture to each radiant heater 45.
The inner end of each tube or sleeve 43 adjacent
to the heater cavity 4l is internally threaded to
receive an exteriorly threaded part of a gas dis
tributor tip 52 formed of refractory material.
The gas mixture in the tubes 43 is subdivided into
perature cement, for example. The refractory
shapes 62 are U-shaped in section and disposed
one above the other so that the longer closed sides
thereof are substantially in alignment to provide
heat radiating surfaces at the side walls of the
kiln chamber substantially coextensive in height
with the maximum vertical loading of the goods
a plurality of gas streams by a plurality of slots
or wares on the cars i8. The shorter legs of the
or channels 53 formed about the periphery of
refractory shapes 62 cooperate with refractory
and extending lengthwise of the narrow part of
brick of the kiln structure to form the longitu
the distributor tip 52. The outlet ends of the
dinally extending passages or flues 5l. The re
channels 53 at the underside of the enlarged end
fractory shapes 62 are preferably formed of a re
of the tips 52 flare outwardly toward the inner
fractory material having good thermal conduct~
Wall surfaces 5d of the heater cavities 4l.
ing properties, such as silicon carbide, for ex
The gas mixture is discharged from the outlet 65 ample, to promote heat transfer from the heated
ends of the channels 53 at the undersides of the
gases through the inside walls of the flues 6l to
enlarged ends of the tips 52, and it is at these re
the goods or Wares passing through the preheat
gions that the iiames are produced and main
ing section l5.
tained. The individual flames produced at the
The fiues 6| in the preheating zone l5 com
tips 52 nare outwardly and project into the cavi 70 municate with vertical nues t3 and 64 formed in
ties or spaces 4l alongside of the outwardly flar
lthe kiln side walls adjacent to the entrance
ing wall surfaces 54. The gas flames maintained
vestibule 26, as best shown in Fig. 1. To the up
at the tips 52 effect such heating of the inner wall
per ends of the vertical hues 53 and 6d :are con
surfaces 54 that the latter are heated to incan
nected ducts 65 and 66, as shown in Fig. 9, which
75 in turn are connected by a duct 61 to the inlet
of1-'an-.exhaustblower @à which may
anyssuitablewma-nner, asby` an electric motor, forv
ItY will no_wbe seenthat-l the residual heat inv
the-heated .gases passing»„into-.the- horizontal flues
Eil' of the >preheating zonek i5 is effectively-utilized
lt: has been explained»above-Ythatvthe. radiantY
heaters` ‘le in they high temperatureiiiringv zoneL
[email protected] are heatedto a high incandescent temperature
by a gaseous heat producing»medium.î ByV ac-`
complishinga largeopart and preferablysubstan
tially all‘oií the combustion of thegas- mixture»
to effect preheatingïofrthe> goods rnoving'through'-`
in the vVicinìtíes or spaces ßl'adjacent to the Wall»
such zone lto `the high temperature firing «zone iii,
surfacesß?l. of the .radiant heaters 4,0., extremely.
and that theg-ases are thereafter -discharged eX
high combustion. temperatures are developeditol
teriorlyr- of- the kiln lil‘by the exhaust blower t3; 10 heat-„the wallzsurfacesto a highly radiantV con
dition. In this manner a large proportion or
After the goods or~wares are treated- inthe
highte-mperature ñringzone iii, such‘goods then
fraction. of - the. heat. developed and. generated rin,
the*spacesiil-:isrconverted to radiant hea*U which
is projected from the highly incandescent wall
show-n*inthegleft--handV part'of Fig. l0,~ the porti-on 15 surfacesë?i; into the interior of the^ highitempera-A>
tureñringzone ¿Sto effect heating of thegoods.`
of- the»cooling-¿ zone l'tiinmediately adjacent to
or wares passing therethrough oníthe carsiß..
theV í’lringjzone l5- is` formed with relatively thick
In accordance with the present invention,l in
refractory sidewalls ,6% spacedi'rom the metallic
order toV control _the character> of the atmosphere
side walls 350i- the outer-casing to provide ver»
ticallyextending passages l'o‘therebetween. At 20 inthe high temperature firing zone I8', the heatedY
gasesgenerated anddeveloped in the combustion.
theiirst portion ofthe cooling zoneV adjacent toV
pass intothe-coolingzene l? inwhich the tein
perature of the goods is gradually reduced. As
the ñring zone It, the bottom edges of the metal
lic side walls 35yterminate a short distance from
the eXtreme lower ends of the kiln side walls
Gâto provideopenìngs l i through which air from
the surroundings may pass upwardly through the
passages lil. Heat is given up, by the refractory
side walls liâ to the air passing upwardly through
spaces-.or vicinities di are withdrawn exteriorly
ci the. kiln it before sucnheated gases-can be
come anactive component of the atmosphere enf.
veloping the work in the high temperature firing,
zone. in the embodiment of the invention dis?
closed herein, this »is accomplishedçby positioning`
the open end- of> @ach combustion spaceV orA
the passages, 70„ thereby promoting natural draft
cavity di» a-platey eäphaving- an openingtherein
l'eft hand partA of Fig. l0, to effect initial cooling
of the, treated goods passing from the firing
lip» ai formed at the; front face of the.
circulation ofj air over the outer surfaces of the 30 of approximately the> same size as the. cavity
opening,y Each plate 83 is spaced .a short dìSIüance
kiln side wal’l‘öâ', as indicatedby the arrows inthe
vbody «i2 about the cavity opening, so as
to torina gap 235 between the plateßßë'and the
zone I6.
Thesecond orintermediate portion of the cool-V 35 front tacco-f» the block i2.
The gaps. ßäserye-asoutlets for thecornbusf
ing zone, Il isA shown in the right hand part of
tionhspaces or cavities 4l through; which» the
Fig. 10 4and diiTers from the ?lrst portion justV de
heated gases are withdrawn and-diverted‘before
scribed in that vertical passages 'l2 are formed
passingoutwardly through the open ends ofthe
within the refractory side walls ‘13. The thick
ness of the refractory side wall separating the 40 cavitiesY The diverted gases pass through» the
gaps 35 into the vertical nues 55 lwhich arevclosedv
kiln chamber and each passageflâ is considerably
at the upper ends and-communicate at the lower,
lessin thesecond or intermediate portion oí the
ends with the larger horizontal flue5`v‘56, as de»
cooling zone il then in the ñrst portion thereof,
scribed above.
sothatthe temperature oí the goodslwill berre
duced further~> in the secondI` portion by the
withdraw gases from the horizontal flues' 6l in
natural draft circulation or’ air which entersthe
the preheating zone l5 and the latter arear-Y
lower endsofY thepassages at inlets lâ;
ranged to receive heated gases from the horl
As> shown in Fig. 11, the îinalandlast portion
zontal nues 5ev in the firing zone I6, asuction
of the cooling zoneil' is formed by hollow metal
effect may be produced in thehorizontal flues-V
lic shells ‘l5 and 'lâ defining the roof- and sideV
55 and vertical ñues 5fë reflected. back
walls, respectively, of the kiln chamber at the
to the gaps 85.` The plate 83 of eaehradiant
exit> end thereof. Airl to effect the linalvcoolingÀ
heater im is positioned relatively close to the
of the goods Vor wares may be circulated >through
forward edge of the lip Sil; deñning theextreme
the shells ‘l5 and lo in counterílow toV themovef
open end of the cavity 4l, sothat restricted out-.
ment of the goods-toward tlfiegexit4 vestibule Sil,
lets are provided by the gaps 8,5 at which Yregions
asshown in Figs, 1A,V andll. Thismay be ac
the suction effect produced by the blower 6,8_is
complishedg by- introducing air'. into,v the ,shell l5;-`
irubensiiied»` in a manner similarl to the suction
through. suitable openings4 (not shown) formed
in the 4el’idtlfiereofV adjacent, to the .exit >vestilmle
362. Ainrnay alsobe introduced into the shells
'líìthrough suitable conduit connections Tí: pro_..
vided at the bottom partsthereoiadiacent to. the.
exit vestibule 3G. The cooling air is withdrawnV
from thel shellsA T5. andy le; at. regions`A removed
from the exitgvestibule 3D, through conduits` l8r,
wandte, whichfare connected by. a conduit Si»
to the inlet of an exhaust blower 32, as showninA
effect produced at the nozzle of a vaccum cleaner. Y
Since the blocksÁ ¿52 are subjected to, elevated,l
temperatures as high as 2800° F; and higher at
thelinner faces thereof; the plates 83 must not
only-withstand thermal Vshock but ‘provision _must
be made for holding such plates accurately in
i position under all or" theÍ operating conditions
ofthe kiln it».
To this end each refractory blockAZî is con-.
structed in such- a manner thatv the plate 83 as
Fig, 11.
sociated therewitl-rforms a rigidly held part of
Bypreviding the cooling zone il justdescribed; 70 the block. As shown mostclearly in Fig. 8, each,
the temperature of the treatedgoods can bere
‘lock comprisesv a refractory Shape having slots
ducedin several stages without adverselyaffect
orchannels te'extending lengthwise of the shape.
ing;the1goods, sothat. the goods willbe at> ade
at the cut-away corners thereof. TheslotsorV
sired low.. temperature upon reaching the~ exit
channels‘âìä‘ are rnore‘or less U-shaped incross.
vestibule Silgto be discharged-fromthe kiln l 4.
section and formed with outwardly Haring Side
walls to receive tie rods 81 having enlarged end
at which the gas mixture is supplied to the heat
portions 88. The slots ßíì are deeper at the front
and rear ends than at the intermediate portion,
as shown in Figs. '7 and 8, to receive the enlarged
ends 88 of the tie rods 8l.
The tie rods 8l, which are more or less tri
angular-shaped in section, are ñrmly secured in
position in the slots 86, as by high-temperature
cement, for example. When the tie rods are se
cured in position, the refractory Shape and tie
rods embodied therein form the rectangular
shaped block 42 having smooth outer surfaces
at the four sides thereof to facilitate mounting
each such block in the side walls 3E of the high
temperature firing zone I6.
The enlarged forward ends 88 0f the tie rods
ers and the lengths of the individual flames pro
duced in the combustion spaces 4 l. In the opera
tion of the radiant heaters llt, as indicated more
or less diagrammatically in Fig. 13, the inner
cones of different size fiames A1, A2, and A3 al
ways extend more or less along an axis B along
side of the inner wall surface 54. Irrespective
of the lengths of the flames, the inner cones
thereof will always be out of contact with the
wall surface 54.
When the radiant heaters Ml are being op
erated at low capacity and the flames are rela
tively small, the suction effect produced at the
gaps 85 is correspondingly adjusted so as to avoid
pulling the flames from the wall surface 515 and
8l are notched at the inner faces thereof, as in
reducing the effectiveness of the flames in heat
dicated at 89, to receive the cut-away corners of
ing the refractory linings of the heaters to a
the apertured plate 83. The notches 89 accurately
high incandescent temperature. When the pres
position the plates B3 a fixed distance from the 20 sure at which the gas mixture is supplied to the
lips or raised portions 84 at the front faces of
radiant heaters is increased, the suction effect
the burner blocks 632, the plates being secured in
produced at the gaps 85 may also be correspond
position in any suitable manner, as by high-tem
ingly increased.
perature cement.
In radiant heaters of the type illustrated, there
As seen in Figs. 5 and 6, the radiant heaters 25 is a tendency for the individual fiames to bend
40 are in spaced apart relation in the side walls
inwardly toward the axes of the heaters in a
3B and arranged in vertical rows. The refractory
manner similar to the bending of the ribs of
blocks 42 are mounted at the inner portions of
an umbrella when it is fully opened. It has been
the refractory side walls 35 between vertical rows
found that the suction effect produced at the
of refractory blocks Sil which are of less depth 30 gaps 85, which completely encircles the open ends
than the blocks e2, as best shown in Fig. 6.
of the combustion spaces 4l, tends to overcome
Refractory plates e! are arranged between adja
such lifting of the individual flames from the wall
cent vertical rows of radiant heaters dû, the outer
surfaces 5i and promote uniform incandescent
vertical edge portions of which bear against the
heating of the wall surfaces. It has also been
plates S3 fixed to the refractory blocks» 42. The 35 observed that when the radiant heaters ¿it are
refractory plates Si are disposed one above the
being operated at less than maximum capacity,
other in vertical rows and cooperate with the
the areas of the wall surfaces 5i heated to incan
refractory blocks 9o to form vertically extending
descence increases when the suction effect is pro
spaces between adjacent vertical rows of radiant
duced at the gaps t5 to withdraw and divert
burners dil.
heated gases into the vertical fines 55.
The refractory plates Sl are T-shaped in sec
The gas mixture supplied to the radiant heat
tion, as shown in Fig. 6, and the blocks B0 are
ers ¿lli may be a complete mixture in which all
formed with relatively deep slots to receive the
of the combustion supporting gas, such as air,
rearwardly extending legs 92 of such plates. In
for example, is supplied with the combustible gas
this manner the vertical spaces in front of the
to effect substantially complete combustion of
blocks 90 are divided to form two manifolds or
the latter in the combustion spaces or Vicinities
flues 55 each of which communicates with the
ill. Under these conditions the suction effect
gaps 85 in one vertical row of radiant heaters
produced at the gaps B5 may be regulated to
ell. Thus, for each vertical row of radiant heaters
withdraw and divert through the gaps substan
di), the heated gases generated and developed in 50 tially all of the heated gases generated and de
the spaces or cavities @l can be withdrawn
veloped in the combustion spaces, so as to main
through the gaps 35 into the vertical nues 55
tain the regions at the open ends of the spaces
provided at both sides of the heaters.
ll! practically quiescent. When such operation
By producing a suction effect in the vertical
of the radiant heaters fifi is effected, no blast of
nues 55 in the firing Zone I6 which is intensified 55 heated gases can be felt by the hand when it is
at the gaps 85, the pressure at the gaps is below
momentarily placed over the open ends of the
and negative with respect to the pressure prevail
combustion spaces lil. When the suction effect
ling in the combustion spaces or vicinities lll of
produced at the gaps 35 is regulated so as to
the radiant heaters dû. By providing any well
maintain the gases immediateiy in front of the
known control provisions, such as a damper $3 60 open combustion spaces practically quiescent,
in the conduit 6l which is connected to the inlet
heated gases can pass substantially by diffusion
of the exhaust blower 68, as shown in Fig. 9, the
only from the spaces 4l into the interior of the
suction effect produced at the gaps 85 may be ad
high temperature firing zone I â.
justed and controlled. Hence, substantially all
The suction effect produced at the gaps t5 also
or any desired fraction of the heated gases gen 65 may be regulated to minimize the ñow of the`
erated «in the Combustion spaces al can be eifec
heated gases by diffusion from the open ends of
tively withdrawn from said spaces and diverted
the spaces 4l. This may be accomplished by
through the gaps, as diagrammatically indicated
producing a suction effect to reduce the pressure
by the arrows F in Fig. 13, before such gases
in gaps 85 below the pressures prevailing in the
can pass from the combustion spaces 4l through 70 spaces 4l and the regions adjacent to the open
the open ends thereof and become an active com
ends thereof, which. is of such magnitude as to
ponent or constituent of the atmosphere in the
produce a substantial inflow of the atmosphere
firing zone IB.
gases from the firing zone l5 into the open ends
The suction effect produced at the gaps 85 of
of the spaces All, as indicated by the arrows C
the radiant heaters lill is related to the pressure 75 in Fig. 13. Such atmosphere gases drawn into
the'fopen ends 'of- thespaces‘fil ,pass toward `the
ïphere‘rof .the ñring zonet-#Slisrelatively lowpthe
:andV ñow ‘ therethrough, »alongY .with the
.diverted "heated gases, .in al common stream into
purities are >carriedinto theñring zone atmos
extent to which objectionable‘constituents.or im
phere‘ is extremely 'small vandinsufficient- to> ad
versely affect the smooth and'lustrous glazed
the vertical‘flues .-5‘5. .It is »to be understood that
there will aiwaysubewa tendency for-«gases inthe
atmosphere-of the nrin'g zone I6 to'bedrawn
into Y'the open ends of the spaces-4l due tothe
.suction 4effect "producedfatv the gapsßö. :When
a complete gas mixture is supplied to the radiant
heaters 4G, the 'suction yeffect Ais "preferably
properly related to the gas pressure delivery
.pressure tof eiîect substantially complete vcom
doors. 2'! andA 3l, atfthe entrance v.and exit-vesti
bustion ofr-thergas mixture in the spaces or vicini
Vpilaster or wal-l section «58 »between V`the Apre
ties 4I of »the radiant heatersrêß.
firing the ,highy'temperature zone I6, the gas
fmixturesupplied >to the radiant heaters 40 .may
vbaaipartial,mixtureJ andasome of the air to »ac
complish completeburning of the combustible
gaslmay-a be drawn into the spaces or vicinitiesl 4|
.byethesuction pressure produced at the gaps v35.
The admission of air into the ñring zone Iß- may
be due to «leakage or maybe positivelycontrolled,
as will presently be pointed out. Any-air pass
ing:into the ñringzone is heated therein and,
due to'suchpreheating, is capable ofÁ producing , I
higher- combustion Atemperatures at .the radiant
surfaces produced on work.
:During operation-of Vthe kiln - I-4,~the- sliding
bules lZíSfandfBü, respectively, are normally. kept
closed and opened only rfor the purpose of: admit
ti-ngearsv` I8 into the »entrance‘vestibule andre
moving such carsfrom the exit‘vestibule. .The
heating.` zone A-I âfand » the »ñring zone M5` forms. a
constriction in the kiln «cham-ber whereby Vob
jectionable' drift ormovement'of `.the„gases‘lbe
`tween thesekilnesections isminimiZed. :A similar
pilaster or 'wa1l.:section -94f-may be ‘provided at
the Yjuncture of fthe-firing zone IE andthe cool
ing zone l1, -asfs'hown'in=Figs.~1A-and 2A. v:The
'gapsvZ-S between »the `cars I8 and» sides ‘of the slot
at the bottomof-` thef'kilnß. I s 'are' sealed »at~ 24» by
the ~~train of carsyI8«moving‘through1the=fkiln
chamber in abutting relation, as `»previouslyvex
pla-ined. By' providing the` normally closed doors
`at7 the 4entrance '-andfexit vestibules, the» pilasters
heaters Jiii rwhen »drawn into >the -spaces 4|
AInward movement of the heated airinto Vthe
spacesor vicinities .4l of the radiant heaters 40 30
i58~-and194 at each-«end ofthe firing zone- |6,~and
the sealing provisions 24 at‘thel sides of `the’cars
YI-8, the ‘circulation of gases inthe >atmosphere
ispromoted dueto the pressure conditionspre
zone yI 6 » is minimized rwhich ' contributes -' to ' the
enveloping vvthewvork‘ being treated «in theîñring
There isa
productioncf .'high quality glazed surfaces-on
low .pressure regionat the centralparts of the
spaces Jil, adjacent tothe enlarged’ ends .of the
work. ~ -Uncler these " conditions the ñring zone
vailing , in the combustion spaces.
I6 :isñl‘led with gases-Which are impoverished in
.distributor vtips.<ii2, into which gases tend tobe . ' sulphur impurities.
drawn, as indicated diagrammatically by .the
arrowsD in Eig. 13. -Since the suction effect vpro
duced at the gaps~85 is strongest at the periph
er-ieswof the spacesf‘il »and weakest >at the cen
By-providing afkiln likefthe `kiln Mwhichis
relatively gas-tight, that is, akilnlstructureinto
gases containingI air may .bel induced atrthecen
which the-:leakagevoffair linto the Vkiln- chamber
is at aY minimum, `thefpressure in the firing zone
i6 may be maintained slightly below atmospheric
pressure due tothe suction leiîect produced at'the
trai »regionsvof--the - spaces, as> indicated diagram
gaps s85. f Such operation of‘the »kiln‘ I4 differs
tral regions'thereof, anadequate-flowof heated l
matically by the arrows Ein Fig. 13, which supply
from: they usual furnace or kiln operation in which
partrofthe. combustion supporting gas >toeiîect
the gaseous 'atmosphere is at a positiveïpressure
combustion vvof the combustiblegas supplied ina 45 a-nd slightlyl above that off-atmospheric, The fact
partial .mixture to the spaces-ll I _
The kiln; l 4 is especial-ly yuseful in treating'work
.to ,produce glazed surfaces thereon, as inthe
.glost `iiring Y of ceramic ware `'and in vitreous
enamelling, for example.
Such -work vcan be l50
that the'ñring‘zone :it may be‘maintained at a
pressure slightly-below atmospheric can be vad
vantageously utilizedzto promote purging of gases
inl the'nring zone it, :aswill be vpointed outfpres
ñred-,in'theiiring zone lßtohigh temperatures
by vradiant lheat projected vfrom the »radiant
heaters-Mi,-Witliout'the necessity of.` shielding the
Itis to be understoodl that in a continuous
tunnel kiln like that disclosedrherein, it is not
lwork by .a heat transfer wall ot'an'finternally
4íireid muiiie' or- tube,.so that radiant heat transfer
can 'zbe‘aeíected at high temperaturesfrom the
.combustion spaces or 'vicinities -fil whose wall
thexnecessary care Vmust be taken >to keep’air
leakage'into the -kiln chamber to a minimum.
When the extent to which air leaks into thekiln
surfaces are-»heated tothe 4highest possible tem
possible to seal 1the-'firing-zone lß'completely and
chamber-.increases,A the suction ei‘îect produced -at
the gaps 85> maybe increasedíto overcome the ad
verseV affect such air inay'have in tending to re
»ItV no provision were-made for diverting‘and -60 duce the high incandescent temperaturesto which
.withdrawing through -the gaps 85 the heated
the radiant heaters Mi areV heated.
gases generated Yin *the combustion spaces ‘41,
.-When'work is being treatedin thehigh tem
such heated gases cou-1d pass into lthe firing zone
peratureîñring zonei it, the atmosphere therein is
I6 rlandthe objectionable constituents in such
desirablyoxidizing. In such case air admitted
gases, `such as-sulphur dioxide and sulphu-ric acid f 1'" into the'ñring zone vlfì'purges the gasesin `the
fumes, forexarnple, would adversely »affect the
atmosphere enveloping the -work being treated
glazed'or glass-like surfaces produceden .the
and-.also contributes-to the production of high
Work-beingrtreated. However, in firingwwork in
quality glazed'surfaces on the work. Such air,
the high '.temperaturezcne i5, the character of
which may bereferred to as “essential air,” may
heatmosphere .enveloping the work- can'be con- f ' pass-into ltheñring zone or section l-6 by leak
trolled »by 'producing the requisite suction. effect
age. in the normal operation »of the kiln. How
at,thef,gaps.«85, whereby heated gases canv'pass
ever, such~leakage of vair into the ñring zone ~I6
:byidi?fusionronly from ythe spaces *M `.into the
should not be excessive because any-air-over and
flringzone I6. f Since the ratel at which the. heat
above that necessary fte effect ‘ the desired vend
edgases can- passby‘diffusion‘into the atmos
resultfmay be referred 'to'as “unessential-air,”
because such air causes an undesirable drop in
I6, such control being eiîected by the thermo
couple 9?, potentiometer control 99 and control
temperature in the firing zone I5 and does not
devices IUE operatively associated with the valves.
In this manner the desired high temperature may
be maintained in the ñring zone I6, the flow of
the gas mixture supplied to the radiant heaters
serve any useful purpose.
In the kiln I4 of the invention the admission
therein of essential air, when an oxidizing at
mosphere is desired, may be effectively controlled.
Such an arrangement is diagrammatically shown
increasing and decreasing When the temperature
decreases and increases, respectively, from the
desired high temperature.
The damper il?. in conduit Eil is similarly con
trolled through the potentiometer control 99 and
control device IIìii operatively associated there
with and increases and decreases the suction
in Fig. l2 wherein an air admission conduit 95
is provided in vestibule 30, for example. A suit
able damper 96, which may be manually con
trolled, if desired, may be provided in the con
duit 95 for controlling the rate at Which air is
admitted into the cooling zone I'I of the kiln
chamber. By providing a kiln structure which
is reasonably air-tight, the pressure in the ñr
ing zone I6 may be maintained slightly below
pressure at the gaps 85 With increase and de
crease, respectively, in pressure at which the gas
mixture is supplied to the radiant heaters 40.
The damper 95 in conduit 95 for controlling
the admission of air into the cooling Zone I 'I
may be also regulated through the potentiometer
9S and control device Iü?i operatively associated
therewith, whereby the desired admission of air
atmospheric pressure so as to cause movement of
air through the conduit 95 into the cooling zone
I1 and through the latter into the ñring Zone I6
to purge the gases therein.
Such controlled movement of air through the
cooling zone I'I to the ñring zone I5 serves several
useful purposes. First, the air in passing through
the cooling zone eiîects cooling of the treated
goods or Wares therein and, in so doing, gradu
ally becomes heated. Second, such heated air
in entering the ñring zone I6 effects purging of
the gases and does not exercise any undesirable
cooling effect in the firing Zone. Third, when
a partial combustible gas mixture is supplied to
the radiant heaters 4i), and gases from the at
mosphere in the firing zone I6 are drawn into
the spaces 4I to supply any deficiency in the
combustion supporting gas to promote complete
combustion in the spaces QI, the oxidizing gases
of the firing zone atmosphere drawn into the
spaces 4I will be at an elevated temperature,
into the ñring zone Iâ may be regulated to main
tain a suitable oxidizing atmosphere in the lat
ter. When the suction effect produced at the
gaps 85 increases and decreases, the valve 95
moves toward and from its closed position, re
spectively, so that essential air only is supplied to
the ñring zone I5 to purge the gases therein, as
previously explained. It is to be understood, how
ever, that the damper QS may be manually con
trolled so that it will not be influenced by the
temperature in the firing zone IS.
The vertical iiues 55 associated with the radi
ant heaters ¿t are preferably of such size that
the paths of fiow for the diverted heated gases
will be adequate to withdraw practically all of
such heated gases generated and developed in
thereby promoting higher combustion tempera
the combustion spaces 4i when the heaters are
tures at the radiant heaters 4i).
The admission of air through the conduit 95
into the kiln chamber may be automatically con
being operated at maximum capacity. Further,
trolled, if desired, responsive to the temperature
of the firing zone I6. Moreover, such control of
the rate at which air is admitted into the kiln
I4 may be associated with suitable control pro 45
visions for regulating the supply of the corn
bustible gas mixture to the radiant heaters MI
and the suction pressure produced at the gaps 8‘5.
As shown in Fig. l2, this may be accomplished
by providing a control system including a thermo 50
couple 91 arranged Within the ñring Zone I6 so
as to be subjected to the high temperatures pro
duced therein. The thermo-couple is connected
by conductors 98 to a suitable potentiometer con
trol 99 of any Well known and conventional type 55
which is connected by conductors itil to a source
of electrical energy. The potentiometer control
99 may be connected by conductors IIJI and H32
to suitable control devices |03 and |04, such as
servo-motors, for example, operatively associated
with the dampers 93 and 95, respectively. The
potentiometer control 99 may also be connected
by conductors m5 to control devices IUE each ot
the vertical fines 55 are considerably larger in
cross-section than the gaps B5, so that heated
gases will pass at a lower velocity through the
vertical i'lues and give up heat to the side walls
[email protected] in which they are incorporated and also to
the Work through the ilue Walls formed by the
plates 9|. In the event any unburned gases are
withdrawn and diverted from the spaces AI
through the gaps iiä into the flues 55, combustion
of such gases may be completed in the vertical
iiues because the cover plates QI become heated
to an incandescent temperature which is above
the ignition temperature of the combustible gas.
Under such conditions, the fines 55 serve as heat
radiating muiiles and contribute to the heating
of Work in the ñring zone lâ.
When a combustible gas mixture of ordinary
city gas and air is supplied to the radiant heat
ers dil, such gas having a rating of about 550
B. t. u. per cubic foot, the heat radiating regions
or wall surfaces 54 may be heated to a temper
ature of 2806“ F. and higher and are at a high
thermal head for treating work passing through
the firing zone Ië. The cover plates 83 for the
radiant heaters are also heated to a high in
which is operatively associated with a valve l0?
provided in a conduit |03 through which the com 65. candescent temperature which may be in the
neighborhood of about 2500° F. and at a thermal
bustible gas mixture is supplied to the radiant
head slightly below the wall surfaces 5d of the
heaters lili at one of the side Walls 36 of the ñring
combustion spaces di. rThe plates @l for the
vertical ñues 55 are also heated to incandes
In the firing of articles in the high tem
peratures zone Il; to produce glazed surfaces 70 cence and are at a lower thermal head which
may be from about 50° to 109° F. higher than the
thereon, the control system just described is so
temperature of the atmosphere in the firing zone
adjusted‘that the rate of now of the gas mix
ture through the main supply conduits |08 to the
In view of the high temperatures produced at
radiant heaters dû is controlled by the valves I0?
responsive to the temperature in the firing zone 75 the cover plates 33, such cover plates and the
.-tie'rod‘s S‘lf‘of-ther refractory blocks ¿l2 vare prefer
'vably fformed of a refractory material, such as
:silicon~.carbide,'~for example, which is capable of
'holding'up under 'extremely high temperatures
without ldeveloping cracks and also possesses
high-tensile#strength and resistance to thermal
`Yshock. The'refractory plates Si for the vertical
Íluesfëifä also maybe formed of refractory nia
terial consisting entirely or preponderantly oi'
silicon carbide. Since heat transfer is effected 10
>to be distributed unequally between rthe hori
zontal .flues @l in each =kilnfside wall, so :that
each bottom horizontal ñueßi lreceives less than
itsproportionate»> share ofthe vheated gases.
ln order to compensate‘for this unequal division
of 'thc'heated-jgasesflowing through the horizon
tals'ñues'fìl, a row of gas-?red radiantheaters
m9 are-incorporated in the bottom part ofv'each
lside wall of the preheating zone- I5, at‘a portion
thereofV adjacent to the ñring zone i‘ii, as shown
`from 'the ‘heated gases passing through the
in Figs. l, 2 and 9. The radiant heaters £09 ycorn
vertical hues 55 through the cover plates 9i to
ithe ‘interior of the iiring zone l5, it is desirable
`>to provide cover plates Si formed of refractory
priseburner blocks, Isimilar to the-burner blocks
-4-‘2 in the ñring'zone It, which are mounted -in
'the kiln y’side walls directly at «the rear fof :the
materialV possessing vgood thermal conductive
refractory shapes or ltiles »62 forming the bottom
horizontal fluesft l .
The .combustible . gasniixture
'The refractory bodiesYîiZ lof the radiant heaters
»supplied tothe radiant heaters »I-ElB is »subdivided
'fäll'may be Yformed of mullite or any other suit
distributor tips HB `to >produce `a plurality
'able refractory material having poor thermal
of-ñanies tolheat the `inner surfaces of theY radiant
conductive properties, so that the wall surfaces 20 heaters to a high incandescent temperature.
"54 of the combustion spaces All at the front faces
Therefractory shapes `§52 .at'thefbottom hori
Vofthe blocks ¿i2 can be effectively heated to the
contalflues- tl areheated vby the 'heaters »I09'by
highest possible temperatures. r¿The tie rods Si
-both *radiant -and convection heating `compon
effectively Vhold the refractory block d2 together
ents andthe heated gases generated and devel
when the inner faces thereof are heated to a
oped'by. such heaters mixes with the heated gases
»highly radiant condition and -stresses are in
entering the bottomhorizontal flues from the
' ñrin'g Vsection I6. Hence, the >heaters |09 in
duced in the’blocks due to the rear parts re
vinaining lrelatively cool while the regions ad
crease the heating accomplished‘by the'bottom
jacent to andA at'the inner surface 5d are heated
horizontal‘ñues |09 over and above -thatfeffected
to high temperatures.
The tie rods 3'! not only serve to increase the
life of the refractory'blocks :i2 but also maintain
the apertured- plates 33 accurately positioned a
short distance from the raised lips te at the front
faces ofthe blocks. The’ tie rods 3l of high tensile
strength tend to retard cracks developing in the
refractory bodies [l2 and also tend to retard the
vgrowth of cracks after they have once occurred.
Further, when the refractory bodies ¿i2 are sub
jected to repeated thermal shock over a long
interval of time, the tie rods effectively hold
such blocks together and prevent any part being
In order to .promote uniform heating of the
.by the heatedgases passing `therethroughfrom
the vertical iluesäß. .In‘this way' effective
heat transfer is accomplished through the inner
walls ofthe bottom horizontal flueslìfl, thereby
compensating-for »the unequal division of the` gas
f Ypassing «therethrough -from the firing îzone .i6
and 'promoting incre Áuniform heating of -Work
the preheating zone 15in which thereis also
a tendency‘forfthe heatedgasesto riseinto the
upper part thereof.
While -the `exhaust blower'ôß has> been .provided
to,v produce a suction effect at thegaps 35 ofthe
radiant heaters .49 inv theiiring `section f I6, it will
be understood that Vsuch suctioneifect may be
produced‘in any other well known manner, such
goods or wares when the cars i8 pass through the 45 as, for-example, bya steamer air ejector.
kiln chamber from the preheating zone l5 into
the high temperature firing zone le, only a single
radiant heater [email protected] is'provided at the refractory
side walls 3S, adjacent to the bottom 38 at the
extreme inlet end of the'ñring zone it, as shown
inlï’igs. 2 and 5. Adjacent to such `single rad
iant heater ¿it in each refractory sidewall t5
are provided two radiant'heaters ‘it one above
the other. All of the remaining vertical rows
of radiant heaters di! in the side walls 36,
throughoutl the entire length of the firing zone,
include three radiant heaters [email protected] disposed one
above the other. With this arrangement of the
radiant heaters si! in the side Walls of the firing
the temperature of the work is increased
more uniformly to the requisite'high temperature
at which it is desired to fire the work in the
firing zone I3. It is to be understood however,
that the radiant heaters may be distributed along
the refractory side walls 36 in any desired man
ner to produce the requisite heating curve during
movement of the work through the firing zone.
It has previously been explained that the
heated gases passing upwardly in the vertical
' iiues 59 at the inlet end of the firing zone [email protected] are
subdivided by the passages 60 through which the
heated gases pass into the horizontal heat trans
fer ñues t! in the preheating zone t5. Due to
the natural draft or iiue effect in the vertical
:ñues‘59, there is a tendency for the heated gases
En the embodiment of the-:invention shown and
described, the'size of the openingorïaperture in
'the'plate‘fßâ of each-radiant heater is suitably
.related-to the-.opening inltheV cavity 4l at the rim
so'that‘rthe heated gases will be effectively
Withdrawn from the cavity when. a suction eiîect
is produced at the gap Y85. This-is accomplished
in the radiant heaters -éû vbyproviding apertures
.in the plates-33 which- are-slightly less in diameter
55 than the extreme open ends-'of theburner cavities
»dL-as seen in Fig.~6.
Attention is called to my copending Vapplication
Serial No. 663,157, iiled’concurrently‘herewith
which is directed tothe construction `of the
60 burner which is used in the kiln-wall hereof and
attention is also called to my copending appli
cation Serial No. 663,159,-which was l'lled con
currently herewith and which ris directed toa
methodV of firing a kiln’and which has become
Patent . 2,474,301.
Although I have shown and described a single
-crnbodirnent cf‘ the invention, it will be obvious
to those skilled in the art that modiñcationsy and
changes may be made without departing from'the
70 spirit and scope of the invention. Thus, other
lforms of radiant heaters than the radiant heaters
Llt‘disclosed herein may be employed’in which
lthe heat radiating regions are heated to incan
descence by a-gaseous heat producing medium.
75 Also, „the Áprinciples -of Vthe invention >may zbe
"applied equally well to other forms of heating
~~apparatus, such as furnaces or ovens, for example.
Itherefore aim in the. following claims to cover
V:all modifications and changes which fall within
the true spirit and scope of the invention.
What is claimed is:
l. In a continuous tunnel kiln including a pre
heating section, an intermediate high tempera
ture firing section and a cooling section having
an elongated kiln chamber extending there
through, a'plurality of refractory lined radiant
heaters distributed along the ñring section;
means to supply a high temperature gaseous
fuel adjacent to said radiant heaters at vieinities
inv open‘communication with the kiln chamber at
,'th’e firing section Vto heat said heaters to _incan
idescence for radiating heat therefrom into‘the
-chamber; passage means providing vertically
‘i disposed passages in the side walls of the firing
providing ilue passages for withdrawing exterior
ly of the kiln a substantial fraction of the heated
gases developed by said combustion before such
gases become a component of the chamber at
mosphere at the firing section, said structure
being formed to provide a vertical flue passage
in each side wall of the kiln at regions adjacent
to the juncture of the preheating and firing sec
tions through which upward flow of the heated
gases is effected, and a plurality of horizontal flue
passages extending longitudinally of the preheat
ing section at the side walls thereof, said hori
zontal flue passages in each side wall of the pre
heating section being disposed one above the
other and connected to receive heated gases from
one of the vertical fines, said horizontal flues
being effective to promote heating in said pre
heating section of the kiln chamber, and means
for increasing the heating accomplished by the
section which communicate with the vicinities 20 bottom horizontal fiue passages over and above
adjacent toV said radiant heaters, horizontally
that effected by the heating gases passing there
4disposed passages in the walls of the firing section
through from the vertical nue passages.
Vwhich communicate with the vertical passages,
4. The combination set forth in claim 3 in which
- and horizontal passages in the preheating section
said means for increasing the heating accom
communicating with the horizontal passages in 25 plished by the bottom flue passages comprises
„the firing section; and means including an ex»
burners disposed within the flue passages.
lhaust blower connected to the horizontal passages
5. The combination set forth in claim 3 in. which
vin the preheating section to produce a suction
said means for 1ncreasing the heating accom
effect in the passages for diverting from the vicin
plished by the bottom horizontal nue passages
ities into the passages and withdrawing there 30 comprises gas-fired burners of a radiant type
through the burned gaseous fuel tending to pass
from the vicinities into the kiln chamber at the
firing section before such medium becomes an
disposed within the flue passages.
6. The combination set forth in claim 3, in which
the horizontal flue passages in the preheating
active component of the atmosphere in the firing
section; at least the walls of the vertical pas 35 section have refractory walls forming the inner
wall surfaces of the preheating section of the
sages in the firing sectionand the walls of the
kiln chamber, and said means for increasing the
horizontal passages in the preheating section
heating accomplished by the bottom flue pas
forming inner wall surfaces of the ñring and pre
heating sections, respectively.
2. In a continuous tunnel kiln including a pre
sages comprising gas-iired radiant heat elements
disposed therein from which radiant heat is
and a cooling section having an elongated kiln
adapted to be projected against the refractory
walls forming said inner wall surfaces.
_' chamber extending therethrough, heat radiating
7. In a kiln having a, chamber, means forming
heating section, an intermediate firing section
a heat producing wall for said chamber including
means for the firing section of the kiln cham
a series of members provided with surfaces
ber, means for heating said radiating means to
adapted to radiate heat directly to said chamber,
,incandescence by combustion of a gaseous fuel
supply means for a fuel adapted to be burned ad
exposed to the kiln chamber atmosphere at the
jacent said surfaces and thereby heat said sur
firing section, conduit means for supplying the
faces to incandescence, additional members forin
gaseous fuel to effect heating of said radiating
means, exhaust means including structure pro 50 ing passages in said wall, said first-mentioned
members including means forming paths be
viding passages for withdrawing exteriorly of
tween said passages .and surfaces whereby prod
the kiln a substantial fraction of the heated gases
ucts of combustion may be removed from said
developed by said combustion before such gases
surfaces through said paths to said passages, and
` become a component of the chamber atmosphere
means to apply a suction effect to said passages
at the firing section, said structure being formed
so products of combustion may be removed from
to provide at least a portion of said passages in’
said surfaces prior to the time they reach said
said preheating section, said cooling section hav
furnace chamber.
,-1 ing an inlet for air at a, region removed from the
8. In a kiln having a chamber, means forming
» ñring section, temperature` responsive regulating
`means for controlling the supply of the gaseous 60 a heat producing wall for said chamber includ
ing a plurality of members, each member having
fuel through said conduit means, means „asso
a cavity formed therein facing said chamber,
ciated with said regulating means for control
mechanism to supply a fuel to be burned adja
f ling the rate of withdrawal of the heated gases
cent the surfaces of said cavities to heat them
by said exhaust means, and means for control
ling the flow of air through the inlet into said 65 to incandescence and thereby direct radiant heat
into said chamber, meansforming a plurality of
« cooling section.
passageways _in said wall adjacent said cavities,
3. In a continuous tunnel kiln including a pre
means forming restricted paths of ilow between
j heating section, an intermediate firing section
and a cooling section having an elongated kiln
, the edges of , said cavities and said passageways,
l chamber extending therethrough, heat radiating 70 mechanism to apply a suction effect to said pas
sageways and paths to withdraw the products of
means for the ñring section of the kiln chamber,
combustion from said cavities before they min
means for heating said radiating means to in
gle with the atmosphere of said chamber where
candescence by combustion of a gaseous fuel ex
posed to the kiln chamber atmosphere at the fir
by said chamber is heated by radiation from said
ing section, exhaust means including structure
of _. combustion :from .said cavities. through. >said
9. In--a `lrilnhaving a chamber, a heat-producí
-ing- -vvall forv said~chamber -includingfa 4»plurality
»ofe'refractory blocks each» having a cavity formed
passageways before; saidi‘hot :products ¿ofçcom
bustion can enterr said' kiln chamber, -saidgßhdt
products of „combustion heating .the walls fnf; said
passageways Yso 'that the .latter willY supply .addi
therein, means to Amount -said blocks »in rows with
the 'cavities facing» said chamber, a plurality -of
Vfurnace Wall members, means lto mount said mem
bers» in--rows «between 4said blocks, said members
and »the meansto mountvthem cooperating Jto
-form- passagevva-ys between» each row 'of blocks,
tional radiant heat to saidî kilnßchamber;
14. The combination vof ’claim 13 including
means responsive »to the temperaturefof said` kiln
chamber, means to 'adjust said supply means vand
the edges of leach» of `said cavities and» saidy pas~
sageways, and» means to apply- a pressure to said
`passageway-s «that is lessthan the pressure .in the
thereby regulate the amount -o‘f` fuel. supplied :to
said burners, and ¿mechanism operative Yin ac.
cordance With the responses- .of :said >responsive
means to operate saidimeans toadjust.
15. In a kiln having a firingzzone,:means- form
>a~-ki1n having a chamber, refractory " 15 ing- a heat producingk Wall forv s'aidfzone: including
a plurality of radiant ‘heaters each provided
~-m'embers~form-ing the-walls »of- said chamber, re
with a cavity opening vdirectly into Asaid
Vvfra'ctor-y burner blocks located in rows ine-said
zone, means-to supply fuel to be-‘burned closely
Vwalls, said block-s » eachrbeing formed with :acavi
adjacent thesurfaces of said cavities tothereby
ty open intosaidchamber, means to supply a
heat the same to incandescence. -refractory‘mem
`fuel~to~be burned V-irrsaid cavitiesto heat thesame
andfthereby'produceradiant heat `tor-be -projected
bers forming passagevva-ys extending 'between
directly into said'vchamber, refractory parts at
said burners and valong said‘wall, means cooperat
I tached -to«-said. wall.. between‘isaid .bleclrsand-con
ing with said members and said burners to form
`operating with saidfwallito >form passageyvayswith
restricted paths of flow between the edges of
saidiparts »facing said. chamber, said passageways i
said cavities and said passageways through which
being formed. with »openings extending tothe
products of combustion mayñow from said cavi
edges :of saideavities,` .and means to. draw _the
ties to said passageways, and means to withdraw
productsof combustionifrom.saidcavities through
the products of Ycombustion from said cavities
-said openings .intorsaid passageways before said
through said passageways ‘before said products
productsof. combustion. can `enter `said chamber, 30 of combustion can enter Vinto said ñring zone.
said parts beingheatedby..saidproducts of com
16. The combination of claim 15 including
bustion ,so> that Atheyialso,supply radiant heat to
means responsive to the temperature of said'flr.
Asaid chamber.
ing zone, and mechanism operative in accord
Y11. Ina kiln having a chamber,_ a Wall for said
ance with the responses of said means to regu
late said means to supply fuel.
chamber .including .refractoryistructure form»
ing-rows of radiant heat, emitting surfaces„ said
structure including passageways extending .in
17. The combination of claim 1‘5 including
means to supply a desired gas to said firing
zone, said gas being Withdrawn therefrom
through said passageways by said means to with
said Wall between said rows of surfaces and an
\ additional passage.. connecting said ~ passagewaxïs,
said. ipassageways. beingv ,provided` with an open-« 1310 draw along with said products of combustion.
'18. The combination of claim 15 including
means responsive to the temperature of saidY fir~
ing zone, means to control the supply of fuel to
tdheat the same, ,and means to withdraw the
said heaters, means to control the ñow of prod
_products of ,combustion _through said openings 45 ucts of combustion to saidmeans to Withdraw,
ing adjacent vthe. edge .of each radiant .heat .emit
`tingsurface thatthey pass,- means to Vsupply a
fuel.- to` be burned closely adjacent said surfaces
into said passageways and passage before they
and mechanism operative ,in accordance with
the responses of said temperature responsive
means to coordinate the operation of said> two
can get,inta,saidchamber= saidproducts of com
bustine serving to >heat the walls of Said .passage
Waysso that they also lradiate heat to said cham
control means.
1,2. In> Y.a kiln having a` chamber, a Wall for
.saidchamberincluding .structure providing al
ternate-rows of radiant heat emitting burners
The followingireferences .are of record inthe
open to said furnace chamber .andpassageways‘
ñle of this patent.:
said ¿passageways being provided with openings 55
extending adjacent the edges and slightly
infront of -the burners which lie alongside them,
means to supply fuel tobe burned in_said burners
to heat the same. and means to Withdraw the
products of combustion from said burners
thrmigh said openings and passageways before
said products of combustion can enter said kiln
Dressler ______ _,____-July 4, -'19.33
Dreffein ___„_._____,__Jul_y v16, 1935
Robson ________ __,-_July
Ladd ____________ __Aug.
Durieux __________ __Nov.
Hess ___________ „-Sept.
273, 1937
23, Y1938
14,' 1939
17,> 1940
>13. In a kiln having a chamber in which ware
Kienle et al. ___`.„'___Nov.`12,V 1940
is fired, a wall for said chamber including-alter
nate rows of radiant burners each provided with
Boland __________ „Sept 16,> ‘1941
`I-Iess et al. ___, „„„„„ __dan. 6, ¿1942
,Hess et al. . ________ __Jan. Vv6, 1942
Hess _____________ __`June `23, 1942
Hess et al ____________ _;Jan. 18,1944
Blaha ______ ___,.„_„_Mar.> 13,1945
a radiant heating cavity vopening directly into
said chamber and rows of passagevvays extending
in a verticaldirection between> said burners, said
passageways being provided with portions there-Y
>of extending to-theedges of said cavities, means
to supply a fuel to said burners 'to be burnt ‘in
said ’cavities to heat the surfaces of the same
Rice: “Use of -F'uels lin Tunnel Kilns,” ‘The
Clar/worker, Jul-y 1929, pages 126-31, inclusive.
and thereby radiate heat directly to said charn
ber, and means to Withdraw the hot'products 75
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