FIELD OF THE INVENTION:
The present invention is directed to a device for cleaning of coke oven gas generated during
coke making process and utilized in the down stream equipments and processes in steel
plants, to make it free of any fine particles or trace of small amount of impurities such as
the organic compounds like the naphtha, tar, benzene, even when present in gaseous form,
in said coke oven gas. In particular, the invention is directed to a coke oven gas cleaning
device involving a scrubbing tower wherein the BOF gas is cleaned by water by the
mechanism of adhesive separation that brings down the impurities content in the gas to the
minimum and thereby enhancing the life of the ducting used for transporting the coke oven
gas to different user equipments and in a reliable and cost effective manner. The clean
coke oven gas thus obtained reduces deposits in the network of pipelines that carry the gas
to the utilities for its consumption such as ladle drier or mixer burners, flare stack ignition
device to the main burners located at 80 m height eliminating the problems of choking and
/or pressure/flow reduction or resultant shut-downs for overhauling and thus improving the
operating efficiency of the coke oven gas based user facilities and more importantly favours
avoiding unwanted stopping of the flaring of BOF gas and saving environment. The gas
claening device of the invention is thus economic, safe and environment friendly favoring
longer life of the piping network for the distribution of the gas through ducting network at
reduced downtime improving overall efficiency and thus having potential for wide
application in industries.
BACKGROUND ART:
It is well known in the art of Steel making operations in a steel plant that the coke oven gas
is generated in substantial volume during the coke making process in coke oven batteries
2

and its quenching. The coke oven gas so produced is utilized as supplementary fuel gas for
the different equipments in the down stream processes. The coke oven gas is consumed
mainly in the Steel melting shop Ladle driers, Mixer Burners, flare stack burners and all the
reheating furnaces of the downstream rolling mills.
The coke oven gas produced in the coke making process contains many organic compounds
like Naptha, tar, Benzene etc at its originating point, in varied proportions. These
compounds are extracted from the gas near the originating point prior to its distribution
through the network of pipe lines transporting the gas at the different use points spread
all around the steel plant. The conventional process of cleaning does not completely clean
the gas as it carries very small amount of stated organic compounds still present in gaseous
form as impurities. Traces of such impurities in the conventional use of the coke oven gas
causes the compounds to deposit inside the whole network of pipe lines eventually causing
choking of the gas flow or pressure/flow rate reduction while in operation for considerable
period of time. In order to get rid of such situations in the conventional distribution and use
of coke oven gas, the process need to be shut down of auxiliary equipments and to
dismantle and thoroughly clean the deposits inside the network of pipelines, thus causing
expensive loss of production. Moreover, due to repetition of such process of dismantling and
cleaning physically the deposits inside the pipes reduces the life of the pipelines due to
damage over passage of time. Such overhauling and maintenance of the pipelines also
consume much of productive manpower and other resources making the cost of steel as end
product, higher and uncompetitive. A still further disadvantage observed in the conventional
steel making process, that the same coke oven gas being used up in various utilities in BOF
shop, is further sent to a Flare Stack Ignition device where the gas is carried to the flare
stack burners located at a height of 80 meters through a network of pipelines and the
residual gas is burnt away continuously to avoid environmental pollution. But it is a common
experience in the Flare stack ignition system that the pipelines carrying the coke oven gas,
3

containing impurities in the form of the organic compounds as already stated, to the
burners causes frequent choking of the pipelines and thereby causing stoppage of flaring of
BOF gases. As a consequence of such choking of pipelines and stoppage of flaring of the
gas, the harmful gases are released to atmosphere without burning and thus creating
adverse impact to the environment. The servicing of the pipelines to clean the choking could
only be attended with complete shut down. After such cleaning and/shutdown on a few
occasions, the pipelines get damaged severely beyond repair and needed replacement.
There has therefore been a continuous need to develop means to effectively reduce the
level of impurities such as the corrosive and sticky organic compounds like the naptha,
benzene etc even in small traces in gaseous forms present in the Coke oven gas, which
could not be extracted at the originating point by the conventional process, in order to
eliminating choking of distribution pipelines by deposition of such compounds on inner walls
of the pipeline with lapse of time and causing erosion of the pipes or stoppage of flaring of
gas harmful gas before releasing to the atmosphere.
OBJECTS OF THE INVENTION:
The basic object of the present invention is directed to effectively clean the residual small
traces of organic compounds such as naptha, tar or benzene in very small proportions or in
gaseous states in the coke oven gas involving a simple , cost-effective and user friendly
cleaning device .
A still further object of the present invention is directed to cleaning of/minimizing the
contents of organic impurities in coke oven gas and thereby eliminating/minimizing
deposition of such impurities on the inner wall of distribution pipelines for such gases to
thereby avoid choking and or pressure/flow reduction through the pipes or the gas
consuming equipments, corroding the walls of pipes needing frequent overhauling, cleaning
4

of deposits, repair or replacement of the pipes, at different locations in the network, and
thus further avoiding frequent shutdowns.
A further object of the present invention directed to cleaning of coke oven gas to thereby
favour avoiding industrial/environmental pollution by providing mechanism for effective
cleaning of the coke oven gas prior to distribution in the network of pipelines, providing
enhanced reliability and performance of the equipments consuming the coke oven gas as
fuel or other purpose.
A still further object of the present invention is directed to cleaning of/minimizing the
contents of organic impurities in coke oven gas, by simple use of water as a cleaning media
and favouring removing/minimizing the impurities by the mechanism of adhesive
separation.
A still further object of the present invention is directed to cleaning of/minimizing the
contents of organic impurities in coke oven gas by a cleaning device, wherein the separation
process would further reduce pollution due to spillage of unwanted toxic compounds over
the area where the cleaning operation is carried out.
A still further object of the present invention is directed to cleaning of/minimizing the
contents of organic impurities in coke oven gas involving a simple but effective cleaning
device which would be simple in construction and components.
A still further object of the present invention is directed to cleaning of/minimizing the
contents of organic impurities in coke oven gas involving a cleaning device which can be
operated with minimum maintenance and in safe and reliable manner over a longer life
requiring very minimal maintenance for the network of pipeline.
5

A still further object of the present invention is directed to cleaning of/minimizing the
contents of organic impurities involving a cleaning device which would be capable of
working on continuous basis and would be scalable for higher cleaning/processing
capacities by mere adoption of components of matching capacities in said device without
involving any complexity.
A still further object of the present invention is directed to cleaning of/minimizing the
contents of organic impurities involving a cleaning device wherein water can be used for
the cleaning or for the purpose of separation of impurities from coke oven gas and the same
is recycled and reused again after proper treatment and thus needing less quantities of
fresh add-on quantity of water for the process and thus saving the scarce resource/natural
reserve.
SUMMARY OF THE INVENTION:
Thus according to the basic aspect of the present invention there is provided a coke oven
gas cleaning device comprising:
a scrubbing tower having means for water spray gas cleaning , an inlet for the unclean gas
, a cleaned gas outlet and a maintenance drain outlet;
a moisture separator adapted to remove the unwanted water from the cleaned gas
operatively connected to the clean water outlet of said scrubbing tower ; and
6

a dip tank operatively connected to said scrubbing tower for sealing the overflow water line
of the scrubbing tower.
A further aspect of the present invention is directed to a coke oven gas cleaning device
wherein said means for water spray gas cleaning in said scrubber tower comprises two
water inlet lines adapted for two stage scrubbing and a water outlet, spray nozzles for
selectively spraying of the water such as to come in contact with the unclean gas entering
the scrubbing tower.
A still further aspect of said coke oven gas cleaning device wherein clean water is sprayed
at a selected flow rate inside the scrubber and comes out of the scrubber in the form of
particle laden water.
According to a further aspect of the present invention directed to a coke oven gas cleaning
device, wherein said scrubbing tower is made of steel structural and adapted to be installed
ahead of the consumer equipment/network of pipelines feeding many consumer equipments
where clean gas is required to be supplied.
The coke oven gas cleaning device according to the present invention, advantageously
adapted to be operated on a continuous basis.
A still further aspect of the present invention directed to a coke oven gas cleaning device
wherein said nozzle means comprising of 2 nos of hollow cone nozzles.
A further aspect of the present invention directed to a coke oven gas cleaning device
wherein the same is adapted such that the water used to clean the gas is recycled and used
again after treatment thereby minimizing wastage of water/natural resources.
7

According to yet another aspect of the present invention there is provided a BOF unit having
operatively connected flare stack ignition device for flaring of BOF gases comprising said
flare stack ignition system operatively connected to network of pipelines supplying the BOF
gases wherein said pipelines are operatively connected to a coke oven gas cleaning device
disclosed above whereby the pipelines are maintained free of chocking and avoiding
unwanted stoppage of desired flaring of BOF gases.
The present invention and its advantages and objectives are described in greater details
with reference to the accompanying non-limiting illustrative drawing.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1: is the schematic illustration of the of Scrubbing tower type gas cleaning device
according to the present invention, used for cleaning of the coke oven gas in steel plants.
DETAILED DESCRIPTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS:
It has already been described that the coke oven gas produced in the coke making process
contains many organic compounds like Naptha, tar, Benzene etc at its originating point, in
varied proportions. These compounds are extracted from the gas near the originating point
prior to its distribution through the network of pipe lines transporting the gas at the
different use points spread all around the steel plant. The conventional process is not
capable of cleaning the gas completely, as it carries very small amount of stated organic
compounds still present in gaseous form as impurities.
8

It is however, of prime concern that the coke oven gas is utilized in a number of utilities and
important equipments where the said gas is used as fuel or for similar other purposes such
as in Steel melting/BOF shop ladle drier, Mixer burners, flare stack burners and all the
reheating furnaces of the downstream rolling mills, said coke oven gas being transported to
the use points through a labyrinth of pipelines distributed through out the steel plants over
long stretches. Traces of organic chemical impurities in the conventional use of the coke
oven gas causes the compounds to deposit inside the whole network of pipe lines eventually
causing choking of the gas flow or pressure/flow rate reduction while in operation for
considerable period of time. In order to get rid of such situations in the conventional
distribution and use of coke oven gas, the process need to be shut down of auxiliary
equipments and to dismantle and thoroughly clean the deposits inside the network of
pipelines, thus causing expensive loss of production. Moreover, due to repetition of such
process of dismantling and cleaning physically the deposits inside the pipes reduces the life
of the pipelines due to damage over passage of time. Such overhauling and maintenance of
the pipelines also consume much of productive manpower and other resources making the
cost of steel as end product, higher and uncompetitive. A still further disadvantage observed
in the conventional steel making process, that the same coke oven gas being used up in
various utilities in BOF shop, is also sent to a Flare Stack Ignition device where the gas is
carried to the flare stack burners located at a height of 80 meters through a network of
pipelines and the residual BOF gas is burnt away continuously using said coke oven gas to
avoid environmental pollution. But it is a common experience in the Flare stack ignition
system that the pipelines carrying the coke oven gas, containing impurities in the form of
the organic compounds as already stated, to the burners causes frequent choking of the
pipelines and thereby causing stoppage of flaring of BOF gases. As a consequence of such
choking of pipelines and stoppage of flaring of the gas, the harmful gases are released to
atmosphere without burning and thus creating adverse impact to the environment.
9

The present invention therefore is directed to make use of a cleaning device and in
particular a Scrubbing tower type gas cleaning device, that is capable to remove the traces
of the said organic chemical impurities, even if in very small amounts in gaseous form, from
the coke oven gas prior to being distributed through the piping network and consumed in
the user equipments in a simple, safe and reliable manner and thus enhancing the life of the
pipelines and equipments avoiding frequent shutdowns due to choking of pipes or
pressure/flow reduction and also environmental pollution caused by stoppage of flaring of
BOF gases in Flare stack Ignition device.
Reference is now invited to the accompanying Figure 1, that schematically illustrates the
Scrubbing tower type gas cleaning device according to the present invention, which is made
of steel structures in the form of a scrubbing tower that is installed before any of the gas
consuming equipment. The unclean gas enters into it and comes in contact with spraying
water from plurality of specially configured Nozzles, mounted inside the tower in selective
position and orientations. Thus the impurities present in the gas is removed by the
mechanism of adhesive separation and brought down to minimum levels. The clean water is
flown through said nozzles at a certain desired flow rate inside the tower and it comes out of
the tower in the form of emulsion of particles of various impurities dispersed into water. The
device of the invention is capable to work on a continuous basis. The device, according to
the present invention is directed to achieve the objective of cleaning/removing unwanted
organic chemical impurities from coke oven gas in a simple, scientific, safe and economical
method before the consumption of said gas in any user equipment.
The device comprises a main Scrubbing tower, which embodies a water spraying gas
cleaning system. The medium used in the device for extracting the extracting the
impurities/compounds from the unclean coke oven gas, is clean industrial water.
Importantly also, the device provides for a moisture separator that removes extra unwanted
10

moisture/water from the cleaned gas. A dip tank is provided at the outside bottom portion
of the scrubbing tower for sealing the over-flow water line. Additionally, the scrubbing tower
is provided with the unclean gas inlet line, the cleaned gas outlet line and a maintenance
drain-out line. All these arrangements are shown schematically in the accompanying Figure
1. The unclean water entering the scrubbing tower comes in contact with the water sprayed
from the specially designed nozzles, wherein clean water is sprayed at a desired flow rate
that removes the particles of impurities in the coke oven gas by the mechanism of adhesive
separation and goes out through the water outlet in the form of suspension of particles in
water.
The scrubbing tower type gas cleaning device of the present invention is also adapted to
provide the option of scalability in its design and construction such that the device can serve
to feed clean coke oven gas to not only one consumer equipment but to a network of
pipelines catering to a number of downstream user equipments. Such modification of the
device need only the increasing the size and capacities of the individual components used in
the system according to the flow requirements. The device of the invention is moreover,
adapted to accommodate a water recycling system to save on fresh supply of scarcely
available clean water, when serving the entire network of pipelines for distribution of
cleaned gas. The scrubbing tower type cleaning device of the invention is thus capable to
provide desired cleanliness of the coke oven gas worthy of safe consumption in various
utilities an equipments in the steel plant on a continuous basis, ensuring reliability and
efficiency of the individual equipments, less downtime costs and improved productivity of
the BOF shop in steel plants.
11

WE CLAIM:
1. A coke oven gas cleaning device comprising:
a scrubbing tower having means for water spray gas cleaning , an inlet for the
unclean gas, a cleaned gas outlet and a maintenance drain outlet;
a moisture separator adapted to remove the unwanted water from the cleaned gas
operatively connected to the clean water outlet of said scrubbing tower; and
a dip tank operatively connected to said scrubbing tower for sealing the overflow
water line of the scrubbing tower.
2. A coke oven gas cleaning device as claimed in claim 1 wherein said means for water
spray gas cleaning in said scrubber tower comprises of a water outlet line, spray nozzles
for selectively spraying of the water such as to come in contact with the unclean gas
entering the scrubbing tower.
3. A coke oven gas cleaning device as claimed in anyone of claims 1 or 2 wherein clean
water is sprayed at a selected flow rate inside the scrubber and comes out of the scrubber
in the form of particle laden water.
4. A coke oven gas cleaning device as claimed in anyone of claims 1 to 3 wherein said
scrubbing tower is made of steel structural and adapted to be installed ahead of the
consumer equipment/network of pipelines feeding many consumer equipments where
clean gas is required to be supplied.
12

13
5. A coke oven gas cleaning device as claimed in anyone of claims 1 to 4 adapted to be
operated on a continuous basis.
6. A coke oven gas cleaning device as claimed in anyone of claims 1 to 5 wherein said
nozzle means comprises of 2 nos of hollow cone nozzles.
7. A coke oven gas cleaning device as claimed in anyone of claims 1 to 6 wherein the same
is adapted such that the water used to clean the gas is recycled and used again after
treatment thereby minimizing wastage of water/natural resources.
8. A BOF unit having flare stack ignition device for flaring of BOF gases comprising said flare
stack ignition system operatively connected to network of pipelines supplying the BOF
gases wherein said pipelines are operatively connected to a coke oven gas cleaning
device as claimed in anyone of claims 1 to 7 whereby the pipelines are maintained free of
chocking and avoiding unwanted stoppage of desired flaring of BOF gases.
9. A coke oven gas cleaning device substantially as herein described and illustrated with
reference to the accompanying figure.

A coke oven gas cleaning device for cleaning of coke oven gas, utilized in the down stream
equipments and processes in steel plants, to make it free of any fine particles or trace of
small amount of impurities such as the organic compounds like the naphtha, tar, benzene,
even when present in gaseous form, in said coke oven gas. In particular, the invention is
directed to a coke oven gas cleaning device involving a scrubbing tower wherein the BOF
gas is cleaned by water by the mechanism of adhesive separation that brings down the
impurities content in the gas to the minimum and thereby enhancing the life of the ducting
used for transporting the coke oven gas. Said cleaned coke oven gas is used in a flare stack
ignition device to the main burners located at 80 m height eliminating the problems of
choking and /or pressure/flow reduction or resultant shut-downs, improving the operating
efficiency and avoiding unwanted stopping of the flaring of BOF gas, saving environment.