Coke oven having an offset expansion joint and method of installation thereof

An offset expansion joint and method of installing the same in a repaired or rebuilt furnace, such as a coke oven or the like, comprises at least two segments of ceramic fiber spaced laterally from one another and separated by silica bricks and a barrier of silica mortar which extends along an edge of each segment and along an edge of each of the bricks by which the segments are spaced, the silica mortar having the ability to set up when exposed to about 2200.degree. F. to prevent passage of gas through the expansion joint in the area of the horizontal flue of the coke oven.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to expansion joints and particularly to expansion 
joints for coke ovens. More particularly, the invention concerns a new 
offset expansion joint for installation in the brickwork in the area of 
the horizontal flue during repair or rehabilitation of coke ovens, 
especially those designed by Koppers, Carl Still, Otto, Wilputte, Didier 
and Nippon Steel. The invention also relates to the method of installing 
the offset expansion joint. 
2. Brief Description of the Prior Art 
Until about 1970, most coke oven batteries in the United States were 4 
meter batteries which were built for an expected life of about 20 years. 
In the 1970's the industry began to install batteries which were greater 
than 5 meters, and usually were 6 meters, which have about an 8-10 year 
life span based upon industry experience, at which time they must be 
repaired or rehabilitated. 
It was expected that the techniques previously used to repair prior 4 meter 
batteries, namely rebuilding of the oven walls using various types of 
compressible material disposed in horizontal cross-section in the 
brickwork, could be applied to the 6 meter batteries. However, these 
techniques have not been completely successful. 
As is well known, it is important to prohibit the leakage of raw coke oven 
gas from the oven chambers through the oven brickwork into the flue 
chambers. Such flue gas leakage is generally attributed to excessive 
spacing or gaps between bricks. The main reason for flue gas leakage 
occurs at the interface between old brickwork and new brickwork. 
Leakage of coke oven gas into the flues may result in ignition, causing 
temperatures in excess of oven design which would destroy the silica 
brick. In addition, if the gases do not ignite totally within the flue 
system, but are evacuated to atmosphere through the waste heat stack, such 
gases may result in violation of government standards, such as the 
Environmental Protection Act, which may require the installation of 
expensive electrostatic precipitators in the waste heat system. 
Due to the unpredictability of the expansion of the old brick and the new 
brick used in rebuilding the larger size coke ovens, the compressible 
materials installed using prior techniques are insufficient to prevent 
leakage of the coke oven gases. In the past, expansion joints of various 
materials, such as wood, spun silica, compressible mortar or the like have 
been used between bricks in adjacent tiers of a coke oven, but never in an 
offset relationship. It has now been recognized by the inventor that a new 
type expansion joint was needed to compensate for the unpredictable 
expansion of new brick when heated. 
SUMMARY OF THE INVENTION 
The present invention comprises an offset expansion joint for use in the 
brickwork of ovens, and particularly in the repair of coke oven walls 
between the old brick and the new brick. The expansion joint is 
constructed of a plurality of segments of ceramic fiber, preferably in the 
form of mats, placed in offset relationship to the existing silica 
brickwork and separated by a silica mortar which acts as a slip joint in 
the arrangement. The preferred ceramic fiber is spun silica and functions 
as a compressible refractory in the brickwork. 
The improved expansion joint is useful in a brickwork construction of the 
vertical flue in the area of the horizontal flue chamber of a coke oven, 
the top of which is formed by a first tier of brick wherein the brickwork 
is subject to unpredictable expansion upon an increase in temperature. The 
expansion joint comprises a brick in a second tier of brickwork below and 
spaced from said first tier brick and forming an inner wall of the flue 
chamber and an outer wall of a coke oven chamber. A first segment of 
ceramic fiber is positioned on said second tier brick and within the space 
between the first tier brick and the second tier brick. The inner edge of 
the first segment is generally aligned with the inner edge of the second 
tier brick and the outer edge of the segment is generally aligned with the 
outer edge of the first tier brick which forms the top of the flue 
chamber. An outer brick in the first tier of brickwork has an outer edge 
in alignment with and forms a portion of the wall of the coke oven chamber 
and has an inner edge in abutment with the outer edge of the first segment 
and the outer edge of the first tier brick which forms the top of the flue 
chamber in the first tier. A second segment of ceramic fiber is positioned 
on the outer brick in the first tier, the inner edge of the second segment 
being in abutment with the outer edge of the first tier brick and the 
outer edge of the second segment being aligned with and forming a portion 
of the wall of the coke oven chamber. A brick in a third tier above the 
first tier brick is positioned on the first tier brick and the second 
segment, the outer edge of the third tier brick forming a portion of the 
coke oven wall. The first and second segments are offset from one another 
laterally and a common barrier composed of silica mortar extends along the 
outer edge of the first segment, the inner edge of the second segment, the 
outer edge of the first tier brick and the inner edge of the outer brick 
in the first tier to form a slip joint. The mortar is characterized by its 
ability, upon exposure to a temperature of about 2200.degree. F. for a 
sufficient time, to set up to prevent leakage of gas through the brickwork 
in the area of the expansion joint for the horizontal flue. Preferably, 
each of the segments comprises a batt of ceramic fiber, and more 
preferably a batt of spun silica. An expansion joint according to the 
invention is preferably located in the horizontal flue area on each side 
of the horizontal flue chamber. 
The method of installing the offset expansion joint in accordance with the 
invention comprises, in the construction of the vertical flue brickwork in 
a coke oven in the area of the horizontal flue chamber to prevent leakage 
of gas from the oven chamber into the horizontal flue chamber through the 
bricks of an existing or new tier of refractory brick, supporting a first 
tier of brick of inner and outer brick which defines the top of the 
horizontal flue chamber from the roof of the coke oven. A second tier of 
brick is built up on both sides of the flue to an elevation adjacent and 
below the first tier. By alternately supporting the outer bricks of the 
first tier on each side of the flue, a first segment of ceramic fiber is 
placed on the second tier brick and adjacent the first tier brick. The 
inner edge of the first segment is generally aligned with the inner edge 
of the flue and the outer edge of the segment is generally aligned with 
the outer edge of the first tier brick. Generally the bottom and top edges 
of the second tier brick are coated with mortar. According to the 
invention, the exposed edge of the first segment and the first tier brick 
are also coated with a silica mortar to provide a barrier forming a slip 
joint. When the support is removed, the outer brick is positioned on the 
second tier brick in such a way that one edge of the outer brick is in 
abutment with the silica mortar barrier formed by the coated segment and 
the opposite edge of the outer brick is in alignment with the outer edge 
of the second tier brick forming a portion of the coke oven wall. A second 
segment of ceramic fiber is disposed on the top surface of the outer brick 
such that one edge of the segment is in abutment with the barrier of the 
coated first tier brick and the opposite edge is in alignment with the 
edge of the outer brick and forms a portion of the wall of the coke oven. 
The segment fits between the top surface of the outer first tier brick and 
the bottom surface of an upper brick forming a portion of the coke oven 
wall. The method of installing the segments of the horizontal flue is 
carried out at the same time on opposite sides of the flue to provide 
expansion joints in the walls of adjacent coke oven chambers of a coke 
oven battery. 
Since expansion of silica brick occurs at approximately 1400.degree. F. and 
the silica mortar does not thermally set until a temperature of 
approximately 2200.degree. F. is reached, expansion of the brick takes 
place as the oven wall is heating up, compressing the ceramic fiber with 
the brick therebetween and slipping along the mortar joint barrier. When a 
temperature of approximately 2200.degree. F. is reached, the silica mortar 
sets up causing a compression of the joint and creating a gas tight 
impermeable barrier through the brickwork from the oven chamber to the 
flue chambers of the coke oven. 
The offset expansion joint of the present invention is applicable to all 
known coke ovens, including those of Koppers, Carl Still, Otto, Wilputte, 
Didier and Nippon Steel. The invention is useful in any coke oven flue 
design including those of the single divided, double divided, hairpin, and 
Koppers-Becker type.

DESCRIPTION OF A PRESENTLY PREFERRED EMBODIMENT OF THE INVENTION 
Referring to FIG. 1, a portion of a vertical flue 10 between two ovens 12, 
14 of a typical Koopers design illustrates the conventional brickwork 
pattern in a coke oven battery. A plurality of tiers of brickwork is 
provided above the coke oven floor portion 15 of the battery forming the 
vertical flue. A plurality of vertical flues connect into a horizontal 
flue 16 at about tier 69 identified on FIG. 1. The horizontal flue runs 
through tiers 67-70 and permits passage of gas from one set of vertical 
flues to another in the battery in the conventional manner according to 
the design of the oven. As is well known, the direction of gas flow is 
reversible from time to time. 
FIGS. 2-8 show, in enlargement, the conventional configuration of the 
bricks in tiers 67-72 of the vertical flue of FIG. 1 prior to the 
installation of the offset expansion joint according to the present 
invention. Referring particularly to those figures, the brickwork adjacent 
the horizontal flue 16 comprises a plurality of tiers of interlocking 
refractory bricks. One side of the horizontal flue is defined by bricks 
18, 20, 22 and 24. The top of the horizontal flue is formed by bricks 26, 
28, 30 and 42. For convenience, the brickwork forming the opposite side of 
the horizontal flue is the same except of opposite hand and is indicated 
by the same reference numerals with a prime (') added. Bricks 26 and 30 
have a center opening 32 for visual inspection. 
The expansion joint according to the invention is an overlap expansion 
joint as shown in FIGS. 9B and 10. The refractory bricks 20, 20'; 22, 22'; 
and 24, 24' surround the horizontal flue, as shown in FIGS. 1-8. They also 
form a portion of the walls of the oven chambers 12, 14, respectively. 
The offset expansion joint is installed by a novel method which involves 
supporting the brickwork above the horizontal flue 16. A preferred means 
of support uses a plate 34 depending from a suspension means, such as a 
threaded rod 36, extending through the inspection flue 32 and supported at 
the roof of the oven (not shown). The plate is retained by a nut 33 
threaded to rod 36. An additional plate 35 having a pair of channels 37 is 
secured to rod 36 by nut 39 to support outer bricks 28, 28' as shown in 
FIG. 9A. By supporting the brickwork above the horizontal flue 16, it is 
possible to remove all brickwork therebelow to floor level 15 including 
the brickwork adjacent and forming the walls of the horizontal flue and 
ovens to install the expansion joint utilizing ceramic fiber segments 38, 
40 and 38', 40' in offset relationship, respectively. The segments are 
preferably in the form of spun silica mats and are compressible. 
As shown in FIGS. 9B and 10, for example, segment 38 is placed between 
tiers 70 and 71; segment 40 is placed between tiers 71 and 72. The tier 
numbers given are, of course, only representative and the only criterion 
is that the segments be placed in tiers in the area of the horizontal flue 
between the new brick being built up from the coke oven floor 15 of the 
oven battery and the old brick which is being supported from the roof of 
the battery. To install the offset expansion joint according to the method 
of the invention, it being understood that the brick 26 and the bricks 
above it in the flue are being supported by the suspension means with 
plates 34 and 35 with channels 37, the bricks are built from the floor 
level portion to the level of tier 70, for example, with the bricks being 
mortared as in conventional practice. 
When the bricks 22, 22' of tier 69, for example, are in place, it is 
desirable to continue the work on both sides of the horizontal flue area 
at the same time. On one side, according to this method, the bricks 28' 
are wedged longitudinally by wooden wedges or the like (not shown) while 
brick 24 is placed on the opposite side. 
A first mat or segment 38 of ceramic fiber, such as spun silica, is 
installed in the space, which has been previously calculated, between the 
top of the brick 24 and the bottom of the brick 26 with the outer edge of 
segment 38 being vertically aligned with the outer edge of the brick 26. 
The exposed outer edges of the brick and the segment are thoroughly coated 
with a silica mortar. Next, brick 28 is then mortared conventionally, 
plate 35 with channels 37 is removed and brick 28 is interlocked to brick 
24, the outer edge of brick 28 forming a portion of the wall of oven 14. A 
second mat or segment 40 of ceramic material, such as spun silica, is 
placed in offset relationship to the first segment 38 and separated 
therefrom by brick 26 as shown. Tier 72 of brick 42 is supported on the 
segment 40 and brick 26 and adjacent brick 30. The common silica mortar 
joint or barrier 44 extends along the edges of segments 38 and 40 abutted 
between brick 24 and brick 26 and bricks 28 and 42, respectively. The 
barrier 44 acts as a slip joint for the expansion joint. Since the mortar 
does not set up until a temperature of approximately 2200.degree. F. is 
reached, the bricks are free to expand and the spun silica segments are 
compressed to prevent passage of gas from within the oven 14 to the flue. 
When a temperature of approximately 1400.degree. F. is reached, and 
expansion is essentially complete, the continued application of heat to 
the joints results in the solidification of the silica mortar and the 
elimination of any air passage through the brickwork between bricks 24, 
26, 28 and 42. The same procedure is followed on the opposite side of the 
flue. Segment 38' is placed, brick 28' which was previously wedged 
longitudinally, is dropped into place and segment 40' is placed between 
bricks 28' and 42'. Of course, as the bricks and segments are placed, they 
are coated with a silica mortar and a barrier 44' of silica mortar which 
acts as a slip joint is formed along the outer edge of segment 38', the 
outer edge of brick 26, the inner edge of brick 28' and the inner edge of 
segment 40'. 
The present invention is especially suitable for use at the interface 
between old and new silica brick, such as when walls in coke ovens are 
repaired and rebuilt. The invention provides a straightforward, relatively 
inexpensive solution to the problem of how to effectively accommodate 
expansion in brickwork whose expansion rates are unpredictable, as well as 
to substantially eliminate passage of gas through the brickwork at the 
interface. The invention is applicable to all known coke oven batteries, 
notwithstanding that they are individually unique. 
Having described presently preferred embodiments of the invention, it may 
be otherwise embodied within the scope of the appended claims.