Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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ARRANGEMENT FOR MINIMIZING LEAKAGE FROM HEATED CHAMBERS
AND METHOD FOR MAKING SA~E __ _ _ _
SPECIFICATION
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TO ALL WHOM IT MAY CONCERN
Be it known, that I, JOSEPH M. EVANS, a citizen of the
United States and a resident of Murrysville, in the County of
Westmoreland and the Commonwealth of Pennsylvania, have invented
new and useful improvements in Arrangement for Minimizing Leakage
from Heated Chamber and Method for Making Same by which this is a
Specification.
BACKGROU D OF THE INVENTION
FIELD OF THE 'INVENTI'ON
This invention relates generally to sealing arrangements
and method of making same, and more particularly, sealing
arrangements for heated chambers and methods for making sameG
It is well known especially from Environmental Reports
and the news media tha-t the sealing of ovens which produce noxious
fumes, smoke, dust, etc., is a difficult ar-t. Only recently the
coke industry in the major steel producing area of the United
States has been threatened with a complete shutdown because of
its inability to comply with the new Environmental Regulations
of the Invironmental Protection Agency of the United States of
~merica and the Department of ~nvironmental Resources of the
Commonwealth of Pennsylvania.
An example of a coke oven which presently has sealing
problems~ is a coke oven with a so-called Koppers Door. The
coke oven with the ICoppers Door utilizes an S-shaped seal for
sealing the door against the jamb of the oven. Because of
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irregularities in the jamb and seal, gases from within the coke
oven readily leak past the jamb. In cases where the seal has
been damaged by loading and unloading of coal and coke, gouges
occur therein, which greatly increase the flow of noxious
gases and fumes from the coke oven to the surrounding air. This
leakage from damaged ovens is especially undesirable since the
degree of pollution caused thereby is many fold that of an oven
in preferred condition. However, during long use coke ovens
are damaged by the constant loading and unloading and seal
cleaning, therefore, a larger and larger percentage of the ovens
leak at ever increasing rates.
Another door widely used in the coke industry is the
Wilputte Door. The Wilputte Door has a diaphragm seal and a
jamb with an adjustable screw for making contact more readily
between the jamb and the door. The Wilputte Door also suffers
from the same sort of problems that the Koppers Door does. A
great need is also felt for an improved sealing arrangement therein
R~cent tests have shown that many of the~e doors in
present operation in their present configurations do not permit
operation within the guidelines set by the Department of
Environmental Resources and the Environmental Protection Agency.
The fact of the lack of capability of meeting these requirements
is well known and has threatened to shut down the steel industry
for lack of coke. Therefore, a great need is felt for an improved
door sealing arrangement which would permit operation within
the guidelines of the Environmental Protection Agency of the
Department of Environmental Resources.
There are a great number of other applications where
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leakage Erom ovens and other heated chambers can be cured byuse of my invention such as soaking pits, used for the soaking
of iron ingots during the manufacture of iron and steel, furnaces
and other examples which are too numerous to mention herein.
DESCRIPTION OF THE PRIOR ART AND RESULTS OF NOVELTY SEARCH
A means of attempting to seal a coke oven is disclosed
in U.S. Patent No: 3,875,018 to Calderon in which a collodial
mixture is injected into a passage from which it leaks out in
such a way that during the coking cycle the:miXture becomes gummy
and sticky for sealing crevices between the door and the jamb.
The mixture dehydrates and develops non-wetting and non-adhering
properties by hardening into a strong solid mass. This method
requires a special door design which incorporated channels for
receiving the mixture. Problems have been discovered in the
injection of the mixture into the channel because the mixture
has a tendency to leak out of the channel and past the seal
before it has an opportunity to harden sufficiently.
The novelty search conducted prior to the preparation of
this application turned up U.S. Patent No: 2,279,791, which does
not form the prior art but only teaches the application of a
material which expands when subjected to elevated temperatures.
This material is used to coat the individual wires of a fire
screen. The fire screen thus coated, when exposed to elevated
temperatures causes the material to expand. The expansion closes
the openings between the individual wires of the screen, thereby
restricting the flow of air at these elevated temperatures
through the fire screen.
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Another result of the novelty search is U. S. Patent
No. 3,81~,613 which discloses the use of a refractory composition
for patching the walls of a coke oven. This refractory composition
comprises siliceous aggregate, plastic clay, a chemical binder such
as sodium silicate, chromic acid, boric acid, sodium sulfate,
magnesium sulfate, sodium phosphate and organic binders and finall~,
a source of maganese dioxide. The patching material may be applied
by the trowelling or plastering over a cracked area in the ~all of
the coke oven or by pumping or i-njecting the material into cracks
in the wall or by pneumatically gunning. This patent has the
object of providing a patching material for coke ovens which has
a long lasting bond with used silica brick.
Summary of the Invention
i
In accordance with the present invention there is
provided a heated chamber having at least one opening; closure
means for closing said at least one opening, said closure means
having at least a closed and open position; said closure means
and said opening having surfaces disposed for coming into
proximity of one another in said closed position, said surfaces
forming a primary sealing means for said heated chamber in said
closed position, there being a substance comprising a liquid
silicate applied to at least one of said proximate surfaces,
said substance being an intumescent substance, that is to say,
foaming and expanding upon the application of heat, thereby
25 forming a secondary sealing means between said proximate -
surfaces in said closed position, when said substance is in a
foamed and expanded condition.
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Also in accordance with the invention there is
provided a method of sealing a heated chamber having at least
one opening with closure means therefor, said closure means
forming a primary sealing means for said chamber, comprising the
steps of: applying an intumescent substance, that is to say a
substance which foams and expands upon heating, to at least one
surface between said at least one opening and said closure
means, said substance on foaming and expanding, forming a
secondary sealing means for said chamber, said substance
co~prising a liquid silicate.
The said substance may comprise sodium silicate, and
may comprise a mixture of sodium silicate and glass.
Thus, the present invention relates to the sealing of
heated chambers from which gases, fumes and other noxious materials
may escape. These chambers have at least one opening therein for
receiving contents to be processed therein in some manner. This
opening has préferably some sort of closing element for the gross
sealing thereof from the surrounding atmosphere. This element may
be a door. This door has a primary seal for making at least a
rudimentary seal between the door and the jamb which reduces the
leakage of gases, fumes and other noxious materials from the
chamber to the surrounding environment. In addition to the primary
seal, a secondary seal is provided which is placed or disposed in
such a way as to enhance the sealing function of the primary seal.
In addition, this secondary seal if made from a material which
changes dimensions such as to expand when exposed to heat and
preferably expands to complement or surround the primary seal,
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thereby, grea-tly improving the ability of the primary seal to
contain the gases, fumes and other noxious materials.
This secondary sealing means is preferably applied in a
liquid state and may comprise a material such as liquid sodium
silicate which provides a sealing capability which improves as
the temperature rises because of its property to expand when heated.
The sealing mixture or medium may be formed by mixing
an intumescent material such as sodium silicate to a desired
viscosity which when applied at temperatures before the chamber
is heated will permit an accumulation thick enough to surround
the primary seal when making a seal against the jamb, upon the
closing of the oven door.
Brief Description of the Drawings
Embodiments of the invention will now be described, by
way of example, with reference to the accompanying drawings,
wherein:-
FIGURE 1 is a cross-sectional view of a Koppers oven door
having an S shaped seal and a jamb according to the prior art;
FIGURE 2 illustrates the invention applied to the Koppers
oven door of Figure l;
FIGURE 3 is a cross-sectional view of a Wilputte door
according to the prior art;
FIGURE 4 illustrates the invention applied to the Wilputte
door of Figure 3;
FIGURE 5 is a three dimensional view of a segment of an
S shaped seal showing gas leakage gaps as in the prior art; and
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Figure 6 illustrates the present invention applied in
Figure 5.
DETAILED DESCRIPTION OF THE DRAWINGS
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Referring now to Figure 1, oven walls 10 are shown with
flues 12 therein. ~buttiny the walls are jambs 14. ~aking
contact with the jambs 14 are S shaped seals.
Plungers 18 have springs 20 for urging the S shaped
seals against the jambs 14~ The opposite ends of the S shaped
seals 16, not making contact with the jambs 14, abut a door frame
22 which has a latch 24 for opening, closing, and locking the
door. Also attached to the door frame 22 are retainers 26 which
hold a plug 28 there between. A brickstay 30 abuts the jambs
14 on the sides opposite the oven walls 10.
Referring now to Figure 2, a partial cross section of the
Koppers door of Figure l, is shown having one of the S shaped
seals 16, one of the door jambs 14 and the plug 28. In the area
of the jamb 14 onto which the S shaped seal 16 abuts an
intumescent material 110 is applied. The intumescent material
expands upon exposure to the elevated temperature during the
making of coke. This expansion provides a gas-tight seal between
the jamb 14 and the S shaped seal 16.
As an alternative embodiment also shown in Figure 2
between the plug 28 and the oven wall 10 a mass of intumescent
material 112 is applied. This mass of intumescent material 112
has the same function as the intumescent 110, and will expand
upon exposure to elevated temperatures.
If there are any gouges or cracks or other irregularities
in the jamb 14 or as in the alternative embodiment as shown
in this same Figure 2 in the oven wall 10, the intumescent
material either 110 or 112, as the case may be, will fill these
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gouges, cracks, or other irregularities both upon application
and subsequent thereto, during expansion in the heating process
and form an ext~emely efficient even under these adverse conditions
where the primary seal, the S shaped seal 16 is not operative
satisfactorily.
Figure 3 is similar to Figure 1, in that it shows a prior
art Wilputte door instead of a Koppers door. Moreover, it has a
similar jamb 214 with a diaphragm seal 216 which makes contact
with the jamb 214. The Wilputte door has a plug 218 similar to
the Koppers door of Figure 1~
Figure 4 shows the placement of an intumescent material
310 with a diaphragm seal 216 and the jamb 214 as shown in Fig. 3.
Also in Figure 4 an alternative embodiment of the Wilputte
door according to the present invention is shown, that is,
between the oven wall 10 and the plug 218 another body of
intumescent material 312 is placed for the sealing of the opening
there between.
The intumescent material may be a polverant cellulatable
glass such as ground glass with a high carbon content mixed with
silicate and a clay. The clay is believed to be preferrably
ball clay or china clay which are used because of their fine
texture.
Another formulation of intumescent material which has
been shown to be satisfactory is liquid sodium silicate having a
viscosity of 400 centipoise when blended. The liquid sodium
silicate is preferrably applied directly to the horizontal
surfaces with a pressurized spray gun which produces a fine
atomized discharge such as a portable pressurized sprayer. The
material sprayed on the horizontal surfaces may also be sprayed
with a pressurized spray gun which produces a finely atomized
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discharge and permitted to coat these surfaces to a thickness
of about ten-thousandths of an inch in one pass or, yet more
preferrably, in two passes to a thickness of twenty-thousandths
of an inch. It has been shown that there is little or no
running of the material when applied in this manner. The sodium
silicate adheres to the oven and will produce a seal upon the
application of heat to the intrumescent material which has the
property in its present form of enlarging or expanding upon being
heated thereby making a good seal. On vertical surfaces the
liquid sodium silicate is preferrably blended to a viscosity of
approximately 950 centipoise or combined with granular sodium
silicate to achieve higher viscosities and thixa tropic behavlor
and applied to a heated surface at or above 100C. In certain
applications other materials may be added to the liquid sodium
silicate such that it will more readily adhere to vertical surfaces
and inhibit the tendency to run thereon.
The applicant has found that a viscosity of between 400
to 950 centipoise is adequate for the applications that he has
investigated. However, even lower viscosities may be adequate
and can be determined by experimentation. The applicant also
believes that mixtures having viscosity which decrease as the
shear rate increases will reduce the tendency of the sealer to
run off the surface after it has been applied thereto. Other
methods of applying the liquid sodium silicate or other materials
having intumescent materials may be by the formation of a gasket,
the application of the mixture with a brush or any other applic-
able method, even aerosol sprays may be useful under certain
sets of circumstances and conditions. The applicant has
additionally found that mixture may be applied to the goose neck
portion of a coke oven to effectively seal it as well as a door.
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