FIELD OF INVENTION
The present invention relates to a process for on-line replacement of a damaged
return liquor pipe line in a coke oven plant keeping the production in force.
BACKGROUND OF THE INVENTION
A coke oven battery is normally designed with a single return line coming out of
tar bosh. After a long service, the single circuit returns liquor pipe line becomes
damaged and worn out. Any disturbance in this critical pipe line would lead into
process interruption and the net result is to shut down the production of the
coke oven.
The continuous cooling of the crude coke oven gas is a 24X7 hour process and it
has become impossible for the process people to plan for a maintenance job in
this damaged pipe line.
The working condition of a critical liquor pipe line (1) as shown in fig.l of the
stamp charge coke oven battery 5,6,7 became a very bad shape and as a result
it requires a stopping of production from the batteries for a longer duration to

replace this damaged return liquor pipe line (1). This would lead to the
production loss at 3-5 days per battery block. The production loss per day from
each block is estimated as 600T of coke which translates into procurement of
external coke which will ultimately impact the operating margin of the Steel SBU.
The cost of coke from external market budgets $400 - $600 per tonne.
The present invention emphasize on a new idea to replace the damaged pipe line
in such a way that the daily production of the coke oven remains unchanged.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose a process for on-
line replacement of a damaged return liquor pipe line of the coke oven battery
while keeping the production in force.
Another object of the present invention is to propose a process for on-line
replacement of a damaged return liquor pipe line of the coke oven battery which
helps to constitute a by-pass line for continuation of production in force before
changing the damaged line.

A further object of the present invention is to propose a process for on-line
replacement of a damaged return liquor pipe line of the coke oven battery which
does not interrupt the pipes in the piping network.
A still further object of the present invention is to propose a process for on-line
replacement of a damaged return liquor pipe line of the coke oven battery which
is eco-friendly.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1 - shows a photo view of a damaged return liquor pipe line
Fig.2 - shows a view of pipe lines diagram of the liquor pipe line indicating the
damaged part with dark colored
Fig.3 - shows a view of blanking the pipe of original passage of GCM'A' and
GCM^B'
Fig.4 - shows a view of making 100% blanking with the flexible rubber blank
Fig.5 - shows a photo view of the pipe lines set up of a by-pass line for block 'B'
and a by-pass line for block 'A' and the existing return liquor pipe line
Fig.6 - shows a photo view of pipe lines set up for a blanking of existing pipe
line of GCM 'A' and GCM 'B' block

Fig.7 - shows a photo view of blanking of GCM 'A' original line and dismantled
the damaged pipe and the blanking of GCM 'B' existing line and installation of
GCM 'B's by-pass line
Fig.8 - shows a photo view of dismantled damaged pipe from the existing pipe
line and the worn-out damaged pipe (inset photo)
Fig.9 - shows a photo view of newly installed pipe in place of existing damaged
pipe line of GCM 'A'
Fig. 10- shows a photo view of existing system of liquor passing from tar bosh to
return liquor line through a bleeder
Fig. 11- shows a photo view of installation of a 'T' joint by-pass line for discarding
the existing pipe line
Fig. 12 - shows a photo view of an installed T joint by pass pipe along with a
blanket through the bleeder for blocking the existing pipe line
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in Fig-2, on the top of the coke oven battery gases are collected in a
gas collecting Main 'A' block (2) wherein the water are sprayed from the top of
the chamber to cool the gas temperature and tar liquors are generated in GCM
'A' (2) which are passed by a adjacent tar bosh (3) to the return liquor pipe line
(1) through a bleeder (4). The return liquor line (1) is connected to a common

return line (5) for both A and B in the existing system. The common return line
(5) is connected to a return line strainer (6). Finally the tar liquors are discharged
downward (7) towards cleaning plant for recirculation.
As shown in Fig 3 & 4, the outlets of the tar bosh of the GCM 'A' block and the
block 'B' through the bleeder are being plugged (8,9) with small diameter
metallic plates covered with flexible rubber blank (10) so that the tar cannot pass
through the return line (1) from the GCM 'A' block and similarly the tar cannot
pass to the common line (5) from GCM 'B' block.
One T shaped joint (11) pipe engaged in the bleeder of GCM 'A' block and one
T shaped joint (12) pipe engaged in the bleeder of GCM 'B' block in order to
make by-pass lines. A separate by-pass pipe line (13) is connected from T' joint
(11) of the GCM 'A' to the return line strainer (6) (Fig.5). Similarly a separate by-
pass pipe (14) also is connected from T joint (12) of GCM 'B' block to the return
line strainer (6) (Fig.5). So during operation of the coke oven plant, the return
tar liquor will pass through a by-pass line (13) from the GCM 'A' block and the
return tar liquor will pass through a by-pass line (14) from the GCM 'B' block to
return.
As shown in Fig 7 & 8, the damaged return tar pipe (1) is dismantled for
replacement. A new pipe of same length is installed at the same place with

proper fixing means. After replacement of the new pipe line again old system can
be used by changing the blanking position. The new process of on-line changing
the damaged return tar pipe does not suffer the production of the coke oven
battery.

WE CLAIM
1. A process for on-line replacement of a damaged return liquor pipe line in
the coke oven battery comprising:
- plugging of the existing return tar liquor passage in the bleeder by a
flexible rubber covered metallic plate blank of each gas cleaning main;
- installing a T' shaped pipe on the bleeder of each gas cleaning main to
make a by-pass line;
- setting up a new by-pass connection pipe from the 'T' joint pipe to the
return strainer (6) of each gas cleaning main;
- dismantling the worn out return tar line pipe;
- replacing a new pipe line at the same position with fixing means.
2. The process of on-line replacement of damaged tar liquor pipe line as
claimed in claim 1, wherein after replacing the old worn out pipe by a new
one, again existing line can be operated after changing the position of
rubber blank which discards the by-pass line.

3. The process of on-line replacement of damaged tar liquor pipe line as
claimed in claim 1, wherein any damaged part of return tar pipe line can
be replaced keeping the production of the coke oven battery in force.

The present invention relates to a process for on-line replacement of a damaged
return liquor pipe line in coke oven battery comprising of plugging of the existing
return tar liquor passage in the bleeder by a flexible rubber covered metallic
plate blank of each gas cleaning main; installing a 'T' shaped pipe on the bleeder
of each gas cleaning main to make a by-pass line; setting up a new by-pass
connection pipe from the 'T' joint pipe to the return strainer (6) of each gas
cleaning main and dismantling the worn out return tar pipe line with a
replacement of a new pipe line at the same position with fixing means.