The present invention relates to ejector for degraphitizing oven roofs in coke oven
and in particular to a hot compressed air operated pneumatic ejector for
degraphitizing oven roofs.
It is known that solid graphite deposition under roof of coke ovens take place due
to cracking of volatile matter evolved during the carbonisation process. The
intensity of solid carbon deposition formation usually depends on the amount and
composition of volatile products, their residence time in oven and thermo technical
regime. On an average, the thickness of carbon deposition is increased by 0.1 to
0.2 mm after each coking cycle. Very high temperature of free space and
inefficient degraphitization cause further growth of carbon deposition.
Due to the abovo discussed carbon deposition in coke ovens it is found that the
same usually result in problems in pushing out coke from the oven. In particular
the deposition of carbon lead to serious problems including decrease in oven
charging volume, increase in charging time, sticking of the carbon in the coke
pushing device and also cause pressurisation of the coke oven.
It is known to ise devices installed in pusher cars to degraphitize the oven.
Usually such prccess of roof carbon degraphitization of coke oven is carried out
using either of th 3 following means :
i) Mechanical removal of the carbon deposits by use of graphite cutters fixed
to the pusier ram. These cutters remove the roof carbon during the forward
and backward movement of the pusher ram during pushing operation.
ii) Removal by use of compressed air wherein the compressed air at an
ambient temperature is passed through the nozzle perforation in T shaped
fixtures secured to the pusher ram. The compressed air burns the carbon
deposited on the oven wall and the roof and thereby effectuates the
degraphitization of the roof.
The above discuss ed presently known methods of graphite removal of coke oven
roofs are not found to be effective to the desired extent as the capability of
degraphitization of such systems are not sufficient. Thus the operation of such
known devices was not sufficient to clear the carbon deposits in ovens.
It is thus the basic objective of the present invention to provide for a novel
pneumatic ejector for degraphitization of coke ovens which would have enhanced
capacity of degraphitization than those of presently available devices known in the
art and favour avoiding the problems of graphitization in coke ovens.
Another object of the present invention is to provide for pneumatic ejector for
degraphitization of coke ovens which can be efficiently operated and would be
highly effective in removal of carbon deposits from coke ovens.
Yet another object is to provide a pneumatic ejector which would favour removal
of carbon deposits from coke ovens more scientifically and efficiently.
Yet further object of the present invention is directed to provide a pneumatic
ejector which would be easy to manufacture install and operate and thereby
provide for simpler efficient and cost-effective degraphitization of coke ovens.
Thus according to the present invention there is provided pneumatic ejector for
degraphitization of coke ovens comprising :
an ejector means;
means for supply of hot compressed air to said ejector means ;
means for forcelul discharge of said hot compressed air from said ejector means.
In accordance with a preferred aspect the pneumatic ejector of the invention
comprises.
an ejector means ;
means for supply of compressed air to said ejector means such that the said
compressed air suck in hot air from the oven ; and
means for forcefully discharging the hot compressed air from said ejector means.
Preferably the above pneumatic ejector of the invention is connected to a pusher
ram either releas;ably or permanently
The width of pusher ram is usually 40-50 mm less than the average width of oven.
During the forward movement of the pusher ram (for pushing out coke) as well as
the backward movement hot compressed air is sent through ejector. The supply of
the compressed air through said ejector means is effected such that when the
compressed air at ambient temperature is sent through ejector the same is
adapted to suck iot air from the oven (due to ejector effect). The hot compressed
air discharged from the ejector means is sufficient to burn off graphite much faster
than those of conventional pneumatic device which does not create ejection
effect. Important y, therefore, the pneumatic ejector of the present invention is
developed such :hat the compressed air supply is adapted to suck in hot air from
the oven and thereby the hot compressed air exiting through the ejector means is
used to degraphitize the coke oven. Also volume of air available for combustion
increases by 4-5 fold (refer data).
It is thus possible by way of the improved ejector of the invention to remove
graphite deposit on on the walls and roofs of oven space by burning the same
using the ejector having compressed air line and hot air sucked from the oven.
It is found that the pneumatic ejector of the invention is having enhanced capacity
of degraphitizing to the extent of 4-5 times than that of conventional ejectors used
for degraphitizaton.
The details of the invention, its objects and advantages are explained hereunder
in greater detail in relation to non-limiting exemplary embodiments as discussed
hereunder in relation to the accompanying figures wherein
Fig. 1 illustrates a conventional mechanical graphite cutter known in the art;
Fig. 2 illustrates a conventional compressed air graphite removal system ; and
Fig. 3 is an illustration of the pneumatic ejector for degraphitization of coke oven
roofs and/or walls in accordance with the present invention.
Reference is first invited to Fig.1 which illustrates the presently available
mechanical graphite cutter. As shown such mechanical cutter is basically
comprised of a mechanical cutter (MC) which is screwed to the pusher ram (PR)
preferably by releasable connector means such as screwing means (SM). As
illustrated in said figure the mechanical cutters are adapted to mechanically
remove the roof carbon during the forward and backward movement of the pusher
ram during pusher operation. Thus it cannot remove graphite deposit if cutter
edge is worn out and no physical contact is made.
As distinct from such mechanical cutters it is also known to have compressed air
graphite removal means for degraphitization of coke ovens as illustrated in Fig. 2.
As clearly illustrated in said Fig. 2, in such system compressed air at ambient
temperature passes through the perforations in the T connection (PT) shaped
fixture secured to the pusher ram (PR). Compressed air at ambient temperature is
used in such system to burn the carbon deposits on the oven walls and roof.
As mentioned enrlier, such known compressed air degraphitization means were
found to be not sufficient to meet the requirements of the art and accordingly the
capacity of such compressed air degraphitization means required to be improved
to meet the demands of the gas oven operation.
Reference is now invited to Fig. 3 which is a schematic illustration of the
pneumatic ejector of the present invention. As shown in the said Fig. 3 such a
system is basically comprised of a compressed air line (CAL) which is operatively
connected to an ejector means (EM) for discharge of compressed air. The said
ejector means is adapted to be in operative communication with the oven such
that supply of corr pressed air through said compressed air line simultaneously
sucks hot air from the oven. The hot compressed air is next ejected from the
ejector means for tr e purpose of degraphitization.
As already explained in the ejector system of the invention the graphite deposition
on the walls/roofs cf the oven are burnt by the combination of the compressed air
as well as by the hot air sucked inside the oven which gets heated up inside oven
due to ejection effect of pneumatic degraphitizer. Based on the pressure of
supplied compressod air, flow of total air at the outlet of the ejector can be
increased by 3-4 times thereby increasing the burning rate of the graphite.
The width of the pusher ram is usually 40-50 mm less than average width of the
oven During the forward movement of pressure ram (for pushing out coke) as
well as the backward movement, the compressed air is sent through ejector as
illustrated in Fig. 3. If X m3/hr. of compressed air at ambient temperature is sent
through ejector it would suck about 3 times more hot air which would enter the
oven through the opon door and get heated up to a temperature of about 400-
500°C. Thus by use cf the system of the invention the burning of graphite is much
faster as the same involves a combination effect of the compressed air and the
hot air to burn the graphite which is faster and more effective as compared to the
use of compressed air (at ambient temp.) as in case of known pneumatic ejector.
In particular, it was also noted that the most efficient operation of the ejector was
operated under air pressure of about 4 to 6 atm preferably 5 atm and gap width is
about 1 to 2 mm preferably 1.5 mm.
It is thus possible by way of the improved ejector of the invention to carry out the
degraphitization at enhanced rate by about 4/5 times greater than achieved using
conventional ejectors.
Importantly the improved ejector of the invention is not only efficient as far as
removal of carbon depDsits from oven roof and/or walls are concerned but it is
also simple to install arid use. It is thus possible by use of the improved ejector
system to achieve more efficient and effective degraphitization of coke ovens, roof
and/or walls and thereoy improve the efficiency of such ejector system which
obviously would add to the efficiency of the coke ovens and related technical
involvement.
WE CLAIM :
1. A pneumatic ejector for degraphitization of coke ovens poooo comprising :

an ejector neans;
means for jupply of hot compressed air to said ejector means ;
means for forceful discharge of said hot compressed air from said ejector
means.
2. A pneumatic ejector as claimed in claim 1 comprising :
an ejector means ;
means for supply of compressed air to said ejector means adapted such that
i the said conpressed air suck in hot air from the oven ; and
means for forcefully discharging the hot compressed air from said ejector
means.
3. A pneumatic ejector as claimed in anyone of claims 1 or 2 adapted to be
connected to a pusher ram either releasably or permanently.
4. A pneumatic: ejector as claimed in anyone of claims 1 to 3 wherein it is
connected to the pusher ram which is 40-50 mm less than the average width of
oven.
5. A pneumatic ejector as claimed in anyone of claims 3 to 4 wherein said pusher
area is adapted to move forward (for pushing coke) as well as move backward
and said ejector is adapted discharge said hot compressed air during said
forward and fcackward motion of said pusher ram.
6 A pneumatic ejector as claimed in anyone of claims 1 to 5 wherein the supply
of the compressed air through said ejector means is effected such that when
the compressed air at ambient temperature is sent through ejector the same is
adapted to suck hot air from the oven.
7 A pneumatic ejector as claimed in anyone of claims 1 to 6 wherein said ejector
means is adapted to be in operative communication with the oven such that
supply of compressed air through said compressed air line simultaneously
sucks hot air from the oven.
8. A pneumatic ejector as claimed in anyone of claims 1 to 7 wherein the rate of
sucking of said hot air from the oven by said compressed air is based upon the
flow rate of the compressed air to said ejector.
9. A pneumatic ejector as claimed in anyone of claims 1 to 8 wherein the hot air
ejected from said ejector means is in the temperature range of 400-500°C.
10. A pneunatic ejector as claimed in anyone of claims 1 to 9 wherein the air
pressure of the ejector is about 4 to 6 atm preferably 5 atm and the gap width
is about I to 2 mm preferably 1.5 mm.
11.A pneurratic ejector substantially as hereindescribed and illustrated with
reference to the accompanying figures.

A pneumatic ejector for degraphitization of coke ovens comprising an ejector means; means for supply of hot compressed air to said ejector means;means for forceful discharge of said hot compressed air from said ejector means The ejector is efficient and is highly effective in removal of carbon deposits from coke ovens.