Method and device for feeding purging and degraphitizing air into coke ovens

A method and a device for feeding purging and degraphitizing air into pipes for rich gas leading to the heating walls of coke ovens. In the device a first cross-sectional opening is connected to a pipe for rich gas. This opening can be opened and closed with a first gate and is adapted to initially release only a relatively small cross-sectional aperture for passing purging air therethrough. A second cross-sectional opening is provided in the device, which is connected to the pipe for rich gas. The second opening can be opened and closed with a second gate and is adapted to release successively, with a time delay after the first cross-sectional opening, a relatively larger cross-section for passing degraphitizing air therethrough. An exchangeable screen can be placed in the aperture in the first cross-sectional opening. The degraphitizing air enters the pipe for burning off the graphite deposits resulting from the rich gas. The device and method prevent deflagrations caused by feeding inaccurate amounts of purging air into the pipe for rich gas.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a device for feeding of purging, flushing 
and degraphitizing air to the pipes for rich gas running to individual 
heating walls of coke ovens, where there is to be provided initially the 
release of a comparably small cross-section aperture for the purging air 
and successively the release of a larger cross-section aperture for the 
degraphitizing air. 
2. Brief Description of the Background of the Invention Including Prior Art 
Purging air serves as is known for removal of amounts of residual gas still 
in the pipe after shut-off of the feeding of rich gas. The thereafter fed 
degraphitizing air is to effect a burning off of the graphite deposits 
formed in the nozzles for rich gas and in the pipe for rich gas. However, 
it is in this context required to adjust accurately the amount of purging 
and flushing air in order to avoid deflagrations of inflammable and/or 
explosive mixtures. 
In conventional devices of this kind a box-shaped provision is attached to 
the pipe for rich gas or respectively to an air feeding pipe connected to 
the pipe for rich gas, which box-shaped provision is provided with a flap. 
Usually this flap is connected via a chain to a rod system, which can be 
moved in a longitudinal direction actuated by an actuating provision 
(hydraulic jack or the like). In a first motion of the rod system thereby 
the flap is lifted up by an exactly preset amount and thereby releases the 
opening cross-section for the purging air required. In a later further 
motion of the rod system the flap is then completely lifted such that the 
full cross-section is available for the flowing in of degraphitizing air. 
The closing of the flap is provided by an opposite motion of the rod 
system and by the self-weight of the flap after termination of the 
degraphitizing process. 
It has now been found that in the course of the operation of the coke oven 
battery there are frequently changes in the length of the rod system based 
on the variations in temperature. The changes in the length lead 
frequently to changes in the aperture width of the flap and as a result 
deviations in the amount of purging air occur. This can lead to the 
deflagrations mentioned above, which, unless readjustments are provided in 
time, result in leaks or thrown out nozzles. 
SUMMARY OF THE INVENTION 
1. Purposes of the Invention 
It is an object of the present invention to provide a device assuring that 
independent of possible changes in length of a rod system always the same 
amount of purging air is available. 
It is a further object of the present invention to provide a device for 
purging air, which helps avoiding deflagrations during the flushing of 
pipes for rich gas. 
It is a further object to provide a safe method for the purging and 
degraphitizing of pipes for rich gas. 
These and other objects and advantages of the present invention will become 
evident from the description which follows. 
2. Brief Description of the Invention 
The present invention provides a device for feeding purging and 
degraphitizing air into pipes for rich gas leading to the heating walls of 
coke ovens. A first cross-section opening is connected to the pipe for 
rich gas and the opening can be closed and opened with a first gate and is 
capable of initially releasing a relatively small aperture cross-section 
for passing purging air. A second cross-section opening is also connected 
to the pipe for rich gas and can be closed and opened with a second gate 
and is capable of releasing successively after the first cross-section 
opening has been opened a relatively larger cross-section aperture for 
passing degraphitizing air. 
An exchangeable screen can be placed in the opening of the first 
cross-section and possibly in the opening of the second cross-section. 
There can further be provided a rod system connected to the first and to 
the second gate, where the opening motion of the rods required is larger 
for the second gate as compared to the opening motion for actuating the 
first gate. 
Preferably there is provided a chain system connected to the first gate and 
to the second gate, where the opening motion required of the chain is 
larger for the second gate as compared to the opening motion for actuating 
the first gate. There can further be provided a rod actuating the chain 
system as well as pulleys supporting the chain system. Auxiliary weights 
can be attached to the gates for maintaining the gas pressure during the 
heat-up phase of the coke oven. 
In one aspect of the present invention there is provided a method for 
feeding purging and/or degraphitizing air into a coke oven with heating 
walls. The pipe for rich gas can be expanded to a box-shaped enlargement. 
Two openings for gas such as air can be provided at the box-shaped 
enlargement and each opening can be covered with a separate gate. 
Preferably, the first opening and the second opening are disposed as seats 
at the box-shaped enlargement to provide a tight fit for the corresponding 
gates. Rich gas can be fed to the heating walls of the coke oven and this 
stream of rich gas can be interrupted. Then a first gate can be opened by 
a first motion of a mechanical transmission for allowing purging air to 
enter the pipe for rich gas and a second gate can be opened by a second 
motion of a mechanical transmission for allowing degraphitizing air to 
enter the pipe for rich gas. 
The novel features which are considered as characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawing.

DESCRIPTION OF INVENTION AND PREFERRED EMBODIMENTS 
In accordance with the present invention two cross-sections capable of 
being shut-off with flaps or gates are being provided for the passage of 
purging air or degraphitizing air, which open successively in time with an 
adjustable time interval in between. In accordance with a further feature 
of the invention the initially opening gate serves for the purging air in 
conjunction with an exchangeable screen. The flaps or gates are 
advantageously connected with chains or with a rod system in conventional 
manner, and the degraphitizing air gate opens with a time delay as 
compared with the gate for the purging air. 
The method of the present invention achieves that the gate for the purging 
air is first actuated and is opened substantially completely, where 
temperature induced deviations of the lifting of the gate can be 
disregarded. By way of the available and by the gate released opening in 
any case the by way of the aperture cross-section determined amount of air 
can stream into the pipe for rich gas without variations in quantity. This 
way the formation of inflammable or explosive mixtures as well as the 
thereby caused deflagrations can be prevented effectively. By way of the 
exchangeable screen the required amount of purging air can be changed at 
any time if required. 
After passage of the time provided for the purging of the pipe for rich 
gas, the rods are further actuated and the mechanics of the opening only 
now provide for releasing the gate for the degraphitizing air. Thereby the 
gate for the purging air can be further opened wider, without substantial 
change of the amount of air streaming in, which air now also serves to aid 
the degraphitizing process. 
Referring now to FIG. 1 there is shown the air feed pipe 1 and the pipe 2 
for the rich gas, which is connected to the air feed pipe and which runs 
initially to the corresponding heating wall not shown here. A box-shaped 
provision 3 is disposed at the lower end of the air feed pipe. The 
provision 3 can be provided as a welded or as a cast construction. The 
box-shaped provision 3 is provided in the embodiment shown with two gates 
4 and 5, of which the gate 4 is provided for the purging air and of which 
gate 5 is provided for the degraphitizing air. Chains 6 and 7 engage the 
respective gates. The chains 6 and 7 run over chain guide pulleys 8 and 9 
and are connected at positions 10 and respectively 11 to a rod system 12. 
This rod system is supported by support and guide rolls 13 and 14 and can 
be moved in a longitudinal direction by way of an actuating mechanism not 
shown here. The disposition and guiding of the chains 6 and 7 are provided 
such that upon motion of the rod system 12 in the direction of the arrow A 
initially the gate 4 opens and based on the longer chain only upon further 
motion of the rod system 12 the gate 5 is lifted successively. 
It can be recognized from FIG. 2, that the gate 4 closes an exchangeable 
screen 15, the aperture 16 of which is adapted to the required amount of 
purging air. The gate 4 as well as the gate 5 cooperate with a seal 
inserted into the the box-shaped provision 3. The gates together with 
corresponding seats provide a substantially gas-tight closure. In order to 
provide an assured sealing against the gas pressure prevailing during the 
heating phase, the gates are preferably provided with auxiliary weights 
17. 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of system 
configurations and purging and burning-off procedures differing from the 
type described above. 
While the invention has been illustrated and described as embodied in the 
context of a heating wall of a coke oven, it is not intended to be limited 
to the details shown, since various modifications and structural changes 
may be made without departing in any way from the spirit of the present 
invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.