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Патент USA US2124865

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Patented July 26, 1938
2,124,865
' ‘UNITED "STATES "PATENT, OFFICE‘ PATCHING INTERIOR SURFACES'OF
Y
v
FURNACES
v'li‘redericlr -W. ‘Winkler, Francis X. Mooney, and
Charles‘ R. Kuzell, Clarkdale, and Melvin T.
Mounts, ‘Cottonwood, Ariz., assignors ‘to
Phelps Dodge Corporatiom-New York, N. Y., a
corporation of, New York
.
-
No Drawing. Application October 8, 1937, Serial
'
v
'
'No.
167,978
'
‘
V
13 Claims. (Cl. 265-43)
This invention relates to the "patching of in
terior surfaces of continuously operated furnaces,
We have discovered that a flame-exposed sur
face, such as the arch, sidewall, or uptake of a
- without interrupting or “unduly disturbing the
reverberatory furnace can be successfully patched,
withoutv interruptingthe operation of the furnace,
by applying to such surface successive thin coats
operations thereof. ‘More particularly, this in
5 vention includes a practical method for building
up a patch of refractory material upon a flame
of a pulverized refractory material suspended in
exposed surface of a high temperature continu
water in the form of ‘a. slurry. , To obtain the
‘ ously operated furnace, such as the side walls or
best results, it is important that the particle size
'roof of a metallurgical or glass furnace, without
and chemicalcomposition of, the refractory ma
terial, and the plasticity of the slurrybe properly 10
regulated to effect good adhesion of the deposit
when initially applied, and to effect hot bonding
'10 interrupting the operationv of thefurnace or
superheating the surface to be patched.
; It has heretofore been proposed to patch in~
terior surfaces of such a furnaceduring a period
of. the material after exposure to thelheat of'the
‘furnace. Patching under such conditions does
not involve exceptional‘ problems, but shutting
furnace. ,The exact proportions of particle size
and chemical composition will vary somewhat de 15
pending on the temperature ofthe surface to
which the material is applied, the highest tem-.
perature to which this material is exposed under
, down the furnace for repairs or patching greatly
operating conditions, the durability required of
when the ‘furnace isshut down ‘and while the sur
15 face to be patched isv relatively cool compared
with the normal operating temperatures of the
increases the maintenance'and operating'costs
the patch, and the location and position of the 20
thereof.
surface to be patched; For example‘, if a patch is
to be applied tothe underside of a furnace arch,
It‘ has also been proposed to patch the
interior surface ‘of a furnace while in a heated
state by applying a flame to the surface to be ' better results will ‘be obtained in general, by the
use of a thinner slurry containing more water,
25 then blowing a" granular refractory -material whereas ‘a thicker slurry containing less water is 25
patched to superheat and soften‘th'e surface, and
. against the softened surface in such a manner
that the added refractory becomes embedded in
the softened surfacebeing treated. ‘Such a pro
cedure involves the expense and inconvenience of
30 superheating the surface to be patched and re
quires the use of complicated apparatus tocarry
out the method while the furnace is being oper
ated, This is especially true where the surfaceyto
be patched is not readily accessible from the out
35 side of the furnace and a long operating nozzle is
required.
,
'
‘
v
f
'
'
‘
It is an object of this invention to provide a
method for patching an interior surface of a high
40
temperature furnace during‘ operation’ of the
furnace and without superheating the surface to
be
- 45
patched.
’
.
'
'
'
,55
;
‘
'
‘
30
material composed of a sandstone or commercial
silica high in SiOz, together with ‘asmall amount
of a ?re-clay up to about 1.0%. These refractory
materials, preferably both pulverized to a particle
size such that a major portion thereof will pass 35
through a 200 mesh screen, should be mixed
before application, with a suitable quantity of
water to obtain the desired plasticity. The actual
quantities of water employed may be varied-with
the chemical composition of the refractory ma-; 40
' terials, although it is preferred that the resultant
slurry have ya speci?c gravity of approximately
nace, without interrupting the operation there
of, by spraying successive thin coats of pulverized
refractory/material on the surface to be patched
pneumatic pressure,’ and is easily transported
through ‘a simple delivery pipe to the place of
1.5 to ‘1.9. ,Such a slurry is easily sprayed, using
application.
>
‘-
v45
,,
One very satisfactory. way of making the‘ slurry
is to mix the ?re-clay with a smaller amount of
water than will be required ultimately andto
a
‘
~
subject this mixture to heat and agitation for a‘ 50
A further, object of this invention is the pro
vision of a patching method utilizing a slurry of sufficient time to- obtain. a homogeneous suspen
refractory'material having a particle size suitable sion of the ?re-clay. This clay suspension may
for obtaining good adhesion when applied'to the I then be thoroughly mixed ,withvadditional water
surface. and having a- chemical composition so and pulverized silica to provide a uniform aque
proportioned as to form a durable integral patch. ous ‘suspension or slurry of refractory material
treated surface.
'
.
Weghave discovered that thebest results are
obtained for high temperaturemetallurgical fur
naces constructed of silica by using a refractory
It is also an object of this invention to build
up a patch on a ?ame-exposed surface of a fur
in. such a manner that the patch becomes
thermally bonded and adhesively secured to the
50
preferable for application ' to. a side wall of a
furnace.
2
4,124,005
ready for application. The proportion of fire
clay to silica is preferably maintained within the
limits of about 0.1.to about 10% fire-clay with the
the most durable patch, although the fire-clay
nozzle employed may be a simple tubular mem
ber, such as a- pipe, and ‘because of the use of a
may be omitted. "‘ With 100- parts of dry refrac
slurry ‘does not require special cooling means.
tory- materials, a total ‘of 25 to 70 parts, by
The apparatus is then recharged and a second
coating applied in the same manner over the first
coating. In this way, successive coats of the re
fractory material are applied to the surface to
be patched until the desired thickness of the
patch is built up. Sufficient time should be al
balance silica, on a dry basis, in order to obtain
weight, of water mayhbe employed, depending up
on the location of the surface to be patched.
10
should be maintained-to provide a flow through
the nozzle until after the nozzle has been with
drawn from the furnace and has cooled. The
Another method of preparing the slurry, and
one which may be preferable from the standpoint
of time consumed, is simply to mix water with the
dry refractory materials in an agitating mixer
such as a small cement mixer. This method may
15 also result in a little more accurate proportion
ing of the solids when the slurry is prepared on a
commercial scale.
lowed to elapse between each coating for the
refractory material last applied to set. Usually
a time interval of 5 to 10 minutes between coat
15
ings is sufficient.
In order that the invention may be more fully
1
The method of this invention also may be ap
plied to the patching of furnaces constructed of
20 refractory materials other than silica, for exam
ple magnesite, periclase, or chrome refractories.
Where the invention is' applied to the patching of
understood, a specific example of the preparation
and application of the materials used and found
suitable for the patching of a reverberatory fur 20
nace will be .described. A sandstone which has
been found to be particularly satisfactory is
known as Seligman silica obtained in Arizona
furnaces, such as basic lined converters, con
structed of these other refractories, the chemical ' and analyzing approximately as follows:
25 composition of the solids in the slurry should be
a a
Per cent 25
appropriately varied to obtain the desired adhe
SiO: __________________________ __' _____ __ 94-96
sion and thermal bonding of the patch.
FeO _________________________________ __
1. 0
The slurry may be applied through any available ‘ A1203 ________________________________ __
2. 6
opening in the furnace to the surface to be
CaO_____ ___________________________ ___.
0. 3
patched, or a special opening in the furnace wall
8.0 may
be made for this purpose- An opening 24 This material, after quarrying, is crushed to a
granular form and is’then further reduced by
inches long by 12 inches in height is usually ade
pulverizing in a suitable mill, such as a Raymond
quate. The patching of the furnace is prefer
coal pulverizer, equipped with an air separator
ably carried out while the furnace is being ‘oper
and dust collector. A size of silica particles which
ated
at
a
normal
rate,
although
if
desired,
the
?r
35
ing of the furnacemaybe somewhat reduced or has been found to be satisfactory is as follows:
even entirely discontinued for a short time dur
.
’.
Per cent
ing the patching operation.
Any suitable a'p
paratus for supplying a stream of the slurry
mixed with a gas such as air or steam under
pressure may be used in conjunction with a spray
pipe or nozzle. Suitable forms of apparatus for
this purposev are shown and described in U. S.
Patent #1,574,183 to Bodflsh and U. S. Patent
#1,578,944 to Wilkinson. Various forms of con
45 ventional cement guns may also be used to pro
duce a spray of the slurry under pneumatic
pressure. The nozzle employed need only be a
simple pipe of sufficient length to easily reach the
point of application of the refractory material in
side the furnace, while the operator holds one
On 200 mesh __________________________ __ 22-35
On 300 mesh __________________________ __ 25-40
Through 300 mesh ____________________ __ 53-30
screen was found to pass through a 100'mesh
screen.
A suitable ?re-clay for use with the silica
analyzed approximately as follows:
I
Per cent
SiO2____‘_ _____________ _'_ ______________ __
57.2
A1203 _________________________________ __ 28.23
F620: _________________________________ __
2.42
CaO __________________________________ __
0.12
end of the nozzle and directs its manipulation
MgO___- ______________________________ __
0.91
from outside of ‘the furnace. This nozzle may be
bent at di?erent angles, depending upon the
point of application desired, or it. may be a
Ignition loss _________ __' _______________ __
11.77
55 straight pipe with a de?ecting lip at its end to
direct the spray in the desired direction.
The
40
All of the material remaining on the 200 mesh
Such a fire-clay is preferably prepared for use
by'pulverizing in a suitable mill to a size approx
imately that given'above for the silica. ‘ This
pulverized ?re-clay is then mixed with 1.75 lbs.
particular form of apparatus employed does not ' of water for each pound of ?re-clay and heated
form a part of this invention.
_
The procedure of patching a furnace arch or
60 side wall after the slurry has been mixed and is
ready for use is preferably as follows:
'
The spraying apparatus is charged with a
suitable quantity of slurry, sufficient to apply
a coating 1/3 to 1/2 inch thick to the area desired
to be patched. Air or steam pressure is then
applied to start the flow of slurry through the
delivery nozzle.
As soon as the flow is well es
and agitated for several hours to provide a uni
form and thorough dispersion of the material, 00
and yield a liquid having a specific gravity of
about 1.28.
n
One suitable way of heating and agitating the
water and ?re-clay mixture is to subject it to the
action of a jet of live steam for several hours. 65
In this case, due allowance should be made for
steam condensate when adding the water. This
tablished, the nozzle may be inserted through ‘ clay suspension is then'mixed with powdered silica
the opening in the furnace wall and the tip of and additional water in proper proportions to
70 the nozzle brought into close proximity to the
provide a ratio of about 97% Seligman silica with 70
area to be patched. The nozzle is then manipu
3% ?re-clay, on a dry basis. The mixing of the
lated back and forth to apply the desired thin slurry may be conveniently carried out in any
suitable agitating mixer. The amount of water is
coating and as soon as the charge of slurry is ex
hausted, the nozzle should be quickly withdrawn preferably varied, dependng upon-the point of ap
from the furnace.
The air or steam pressure
plication of the slurry. For patching the under-v
9,124,805
side ofa reverberatory arch a thin slurry would ~
be desired, containing for example .97 lbs. Selig
_ man silica, 8.25 lbs. ?re-clay suspension,v 54.75
lbs. additional water. This would yield a ‘slurry
having a speci?c gravity of approximately 1.6.
It is. preferred to. spray a thin slurryof this
' mixture on the undersidev of a furnace arch under
‘a fairly high pressure, for example, using about
said furnace while said surface is at a normal
temperature for the operation of said furnace.
, 3. The method of patching the interior'of a
high temperature continuously operating metal
lurgical furnace comprising spraying an aqueous
suspension of pulverized refractory material in
35-60 lbs. pressure. About 2 cubic feet of such a
a thin coating on an interior ‘surface of said
furnace while said surface is at a normal tem
an ‘area of 10 to 12 sq. ft. on the underside of the
perature for theoperation of said furnace, allow
ing said coating to set, and subsequently spray 10
10 ‘slurry is suitable for applying a single coating to
‘
. 3
coating of said slurry upon an interior surface of
furnace arch. ~
For preparing‘a slurry to use on side walls or - ing a second thin coating of said material over
said ?rst coating,
uptakes of a reverberatory furnace, a thicker prising principally said refractory material com
silica together with su?icient
slurry is desired and the amount of additional - oxides of aluminum,
iron, andvcalcium to pro
water employed is' preferably about 31.75 lbs.,
15
, duce an integral adhesive thermally bonded de
with 97 lbs. Seligman silica and 8.25 lbs. fire-clay .posit
at, the operating ,temperature »of said
suspension, yielding a slurry having a-speci?c
gravity of approximately 1.8. A higher pressure
20 such as 50-80 lbs. for spraying this slurry against
4. The method of patching the, interior of a
furnace.
After the patch has been built up to the desired
manner.
> ,
.
.
v'I'he slurry, when sprayed as described above on
I the hot surface to be patched, readily sticks to
30
.
‘suspension of pulverized refractory material in
thickness, usually 3 to-6 inches, the side wall '
able
>
beratory furnace comprising spraying an aqueous
-
25, opening. of the furnace may be closedin any suit
,
high temperaturecontinuously operating rever-' 20
the side walls or uptakes mayalso be employed,
because of the greater density.
.
a thin coating on an interior surface of said fur
nace while said surface is at a normal tempera
ture for the operation of said furnace, allowing 25
said coating, to set, and subsequentlyspraying a
second thin coating of said material ‘over said
first coating, saidv refractory
comprising
such. surface. After the refractory material has - principally silicawith a smallmaterial
amount of ?re-clay
set under the heat of the furnace, the patch be
so proportioned thatsaid coatings become ceram 30
comes thermally bonded. If the material em
ically bonded by incipient fusion at thehighest
ployed is too refractory, such bonding will not normal
operating temperature of said furnace.
take place. On the other hand, the refractory _ 5. The method of patching the interiorof a
material in the slurry should not be of such'a high temperature continuously operating rever
chemical composition that it will become softened beratory furnace comprising preparing a slurry
appreciably at thetemperatures of the furnace.
of waterand powdered refractory material, said
A patching methodpin accordance with this in
comprising principally silica with‘ ‘a
ventlon has proved to be practical and highly (material
small
amount
of fire-clay in such‘proportions and
e?icient in actual practice, making possible the of such particle.
size that. a coating thereof be
continuous operation of a reverberatory or similar
ceramically bonded by incipient fusion at
furnace for much longer periods of time than comes
the highest normal operating temperature of said
has been possible heretofore. The aparatus re
furnace,
pneumatically spraying a thin coating
quired is simple and easy to operate, and it is not
necessary either to shut down the furnace for
patching or to superheat the surface being
treated.
The terms and expressions which we have em
ployed are used as terms of description and not of
limitation, and we have no intention, in the use
of such terms and expressions, of excluding any
equivalents of the features shown and described
or portions thereof, but recognize that various
‘ modifications are possible within the scope of the
invention claimed.
We claim:
1. The method of patching the interior of a
high temperature continuously operating furnace
60
comprising preparing a slurry of water and
powdered refractory material, said material com
prising principally silica and being proportioned
chemically to produce an adhesive thermally
bonded deposit at the temperatures of operation
of said furnace,_and pneumatically spraying a
thin coating of said slurry upon an interior sur
65 face of said furnace while said furnace is being
operated.
2. The method of patching the interior of a
high temperature continuously operating furnace
comprising preparing a slurry of water and
powdered refractory material, said material com
prising principally silica and being proportioned
chemically and of such a particle size as to pro
duce an adhesive deposit thermally bonded by
of said slurry upon an interior surface of said
furnace without interrupting the operation of
said furnace.
.
6. A method of hot patching a ?ame-exposed 45
surface of a high temperature continuously op
erating, furnace comprising spraying a slurry of
powdered refractory material and water in a thin
coating on said surface while said furnace is be-'
ing operated, and subsequently spraying succes 50
sive coatings of said slurry over said ?rst coating
to build up a patch of the desired thickness.
7. A method of hot patching a ?ame-exposed
surface of a high temperature continuously op»
erating metallurgical furnace comprising spray 55
ing a slurry of powdered refractory material and
water in a thin coating on said surface while said
surface is at about a normal temperature for
the operation of said furnace, and subsequently
spraying successive coatings of said slurry over 60
said ?rst coating to build up a patch of the
desired thickness, said refractory material com
prising 0.1 to 10% ?re-clay and the balance prin
cipally silica.
8. A method of hot patching a ?ame-exposed
surface of a high temperature continuously op
erating furnace comprising spraying a slurry of
powdered refractory material and water in a thin ‘
coating on said} surface while said surface is ‘at
about a normal temperature for the operation of 70
said furnace, and subsequently spraying succes
incipient fusion at the operating temperatures of ' sive coatings of said slurry over said first coating
said furnace, and pneumatically spraying a thin
35
to build ‘up a patch of the desired thickness, said
refractory material comprising silica witha small 75
4
. amount of ?re-clay and having a particle size
sandstone and'water in the proportions of about
sandstone and about 3% fire-clay on a dry
such that a major portion thereof will pass - 97%
basis to form a slurry having a. speci?c gravity
through a 200 mesh screen.
9. A method of hot patching a flame-exposed» ' of about 1.6 ‘ to about 1.8, and pneumatically
spraying successive thin coats of said slurry upon
surface of a high temperature continuously op
the surface to be patched while said surface is at
crating furnace comprising spraying a slurry of
powdered refractory material and water'in a thin ' a normal temperature for the operation of said
coating on said surface while said surface is'at furnace.
12. A method of hot patching a ?ame-exposed
about a normal temperature for the operation of
10 said furnace, and subsequently spraying succes
sive coatings of said slurry oversaid ?rst coat
ing to build up a patch of the desired thickness,
said refractory material comprising pulverized
surface of a high temperature continuously op 10
erating furnace comprising spraying a slurry of
powdered refractory material and water in a thin
coating on said surface while said furnace is being
operated, and subsequently spraying successive
silica with a small amount of pulverized ?re-clay
coatings of said slurry over said first coating to 16
15 and said slurry containing sufficient water'to 'build up a- patch of the desired thickness, said
provide a speci?c gravity of about 1.5 to about 1.9.
10. A method of hot patching a ?ame-exposed refractory material being of a particle size such
that it will substantially all pass through a 100
surface of a high temperature continuously op
‘
'
erating furnace comprising'spraying a slurry of mesh screen.’
13. The method of hot patching a high tem 20
powdered refractory material and water in a thin perature
continuously operating furnace contain
coating on'sa'id surface while said surface is at
about a normal temperature for the operation of ing molten mineral materials comprising form
ing a uniform mixed slurry of powdered refrac
said furnace, and subsequently spraying succes
sive coatings of said slurry over said first coating tory materials, the chemical composition and
water‘ content of said slurry being‘proportioned
to build up a patch of the desired thickness, said
refractory material comprising a small amount to produce an initially adhesive patch adapted
to vbecome ceramically bonded to a ?ame exposed
up to about 10% ?re-clay with the balance prin
cipally silica and having a particle size such that surface of said furnace. at the‘ highest normal
a major portion thereof will pass through a 200 operating temperature thereof, and pneumatical
ly spraying successive thin coatings of said slurry
30 mesh screen and a substantial proportion thereof on the under surface of the furnace roof while
will pass through a 300 mesh screen.v
‘ ‘
said- surface is at a' temperature approximating
11. A method of hot patching an interior sur
its temperature during normal operation of- the
face of a metallurgical furnace comprising‘pul
verizing separately. high silica sandstone and fire
,35 clay to a- ?neness such that‘ a major‘ portion
thereof will pass through‘ a 200 mesh ‘screen, heat
ing and agitating said ?re-clay with a small
amount of water to provide a uniform suspen
sion, incorporating said suspension with‘ said
furnace.
i.
' FREDERICK W. WINKLERL
FRANCIS X. MOONEY.
CHARLES R. KUZELL.
MELVIN T. MOUNTS.
85
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