Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The invention relates to a method for the production
of coke by dry distillation of coal.
2. DESCRIPTION OF THE PRIOR ART
Conventionally, coal is dry-distilled in a vertical
coke chamber and the coke obtained is expelled into a
quenching car, after which the car is run beneath a coke
quenching tower. It is known for a signal transmitted by
an infra-red detector passed by the car on its way to the
quenching tower to be used to initiate the supply of
quenching water. This infra-red detector is connected a9
an on/off detector, and the spray system in the coke
quenching tower starts to spray when the detector signals
passage of the glowing coke in the quenching car.
Spray installations are generally designed to pro-
duce a constant quantity of quenching water per unit of
time through each of the sprays. The quenching
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installation is therefore arranged to supply quenching
water for a constant quenching period, which period is
adjusted according to the anticipated maximum temperature
arising in the coke and the thickness of the coke layer in
the car. This prevents the presence in the car of any
coke residue still glowing after quenching, which could
lead to after-burning of the coke after the coke has been
emptied onto a quenching chute. One consequence of this
method is that in every case where the average tempera-
ture of the coke in the quenching car is lower than thehighest temperature arising the humidity of the coke be-
comes too high. Furthermore, over-lengthy quenching t mes
can reduce the availability of the quenching tower.
SUMMARY OF THE INVENTION
The object of the present invention is therefore to
provide a method of production of coke in which the amount
of quenching water supplied is adapted to the particular
load of coke on the quenching car.
A further object of the invention is to provide for
control of the heating of the coking chamber in dependence
on the temperature of the coke produced.
The essence of the invention is that the detector
is used to produce an analogue measurement signal of the
surface temperature of the coke in the quenching car,
this signal being used to adjust the quenching time
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required. It has been found that an infra-red detector
can easily be used to obtain an analogue measurement
signal which provides a sufficiently reliable reproduc-
tion of the surface temperature of the coke throughout
S the length of the quenching car. Thus the detector is
used not only for switching the spray system on and off
but the strength of the signal measured determines the
quenching time per passing quenching car.
sy the term "analogue signal" we mean that the
signal comprises quantitative information as to the
surface temperature detected. The actual form of the
signal, which will typically be electrical, may of course
be digital.
A simple method of performing the invention is for
the maximum temperature of coke in the quenching car to
be obtained from the measured signal by electronic means
in a manner which is in itself known, this maximum tem-
perature then being used for setting the required
quenching time. However, the temperature range of the
coke in the car could, as measured, vary widely. Pre-
ferably, therefore variation in the said analogue signal
along the length of the quenching car as the car passes
the detector is used to determine the desired durations
of quenching water supply at a plurality of different
locations along the quenching car.
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It goes without saying that, in this case,
the quenching system adopted must be so designed
that the quenching time is adjustable individually
for each spray or section of sprays in the system.
Thus the invention makes it possible for the
quenching time to be more adequately adjusted to the
requirements of each load of coke on a quenching
car, and in this way an unnecessarily high humidity
in the coke can be avoided. It should be noted that
when a blast furnace charged with coke, it is
important that the humidity in the coke should not
be too high for the efficient operation of the
furnace. It should further be noted that a saving
in quenching time can lead to an extension in the
availability of the quenching tower and therefore to
a reduction in the cycle time of a coke quenching
car.
It has already been mentioned that in the
practice of the invention, the quenching times of
individual sprays or of sections of sprays can be
adjusted on the basis of the temperature variations
measured in the quenching car. It will however be
clear that simpler operation is possible if the
temperature of the coke in the quenching car is
kept as uniform as possible. It is also important
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for optimum operation that the average temperature
of the coke in the ~uenching car~should be as
uniform as possible from one car load to -the next.
This means that the temperature of operation from coke
chamber to coke chamber and within each coke chamber
should be kept as uniformas possible.
~ he average temperature and the temperature
distribution in a col~e chamber depends partly on -the
setting of the burners in -the combustion chambers
between the coke chambers. Attempts have already been
made to set the temperature and the temperature
distribution in coke chambers more accurately by
measuring temperatures in the chambers. For example
it has been proposed to measure the temperature at
various points in each coke chamber using infra-red
detectors after the chamber has been emptied, and to
adjust the setting of the burners on the basis of
this measurement. It is also customary for the
temperature of each burner to be measured directly ~ia
the sight holes on the surface of the furnace, to
obtain an impression of the temperature and temperature
distribution along the wall of the coke chamber. It
has been fo~d that neither method can be regarded
as viable on ergonomic grounds~ and neither has
proved to be sufficiently accurate in practice to provide
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a reliable measurement. ~urthermore, measurement
through the sightholes is very t~me-consuming.
We have now found that the signal measured by
the infra~red detector close to the f~uenching tower
can also be used as a derived measuremen-t of the
temperatl~e alon~ the coke chamber wall. One aspect
of the invention is therefore -that the signal from
the infra~red detector is used for adaus-ting the
temperature distribution along the walls of the coke
ch~nber~ It has even been found possible for local
differences in the heating of the coke chamber to be
determined and adjusted on the basis of variations
in the analogue measurement si~nal from the infra-
red detector along the length of the coke quenching
car.
It should be noted that, cor~monly, the coke in
the quenching car is still burning before it is
quenched in the quenching tower. It is then important
that the flame produced by the coke should not distort
t~e measurement signal. ~his can be avoided by
setting the infra-red detector to detect only the
wavelength of the glowing coke.
~RIE~ D~SCRIP~IO~l~ OF ~{~ DF~ JI~GS
~he preferred erabodiment of the invention will
now be described by way of non-limitative example
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with reference to the accompanying drawing, in which:-
Fig. ~ shows schematically ~arts of a co~ing
plant, in particular the location of an infra-red
detector near a quenching tower, and
~ig. 2 is a block diagram showin~ the processing
of the signal produced by the infra-red detector.
DESCRIPTION OF ~ PRE~RR~ EMBODIMENT
., .
In Fig. 1, there is shown a track 1 along which
a coke quenching car 2 travels in the direction of
the arrow to arrive underneath a quenching tower 4.
The ~uenching car 2 is filled with glowing coke 3
expelled from a conventional coke oven (not shown).
~here is a spray system 5 in the tower 4, from which
quenching water is sprayed on -the mass of coke.
~he quenching car 2~ quenching tower 4 and spray
system 5 are of a conventional known kind.
An infra-red detector 6 is arranged above the
track 1 of the ~uenching car just in ~ront of the
quenching tower. ~he angle of reception of the infra-
red detector and the height at which it is locatedabove the quenching car are such that it receives
an image of a substantial part of the breadth of
the load of coke in the car~
~he control means which processes the signal
received by the infra-red detector is shol~n
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diagrammatically in Fig. 2, which also diagrammatically
shows a burner chamber 7 forming part of the coking
battery. A set of burners8 is shown beneath the cham-
ber. It should be noted that in practice the number
of burners varies from between 20 and 40. Each coking
chamber is located between two such burner chambers 7
and is heated through the partition walls between the
burner chambers and the coking chambers. Fuel is con-
veyed to the burners 8 via a duct 12 and a control
valve 10. The Figure also shows the spray system 5
of quenching tower 4, again schematically with the
supply line 11 for quenching water and the control
valve 9 in this line 11.
The electrical signal 14 obtained from the infra-
red detector 6 is processed by control apparatus indi-
cated by a block 13 into three control signals 15, 16
and 17. Control signal 15 represents a sharp increase
in the measurement signal 14 and is translated via a
relay 18 into a command 21, which causes control valve
9 to be opened. This causes spray system 5 to operate,
as the quenching car 2 continues to run under the
detector 6. The ~ontrol signal 16 is proportional to
the maximum value of the measurement signal 14 and
therefore to the maximum measured temperature of the
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coke 3 in the quenching car 2. The signal 16 is trans-
lated in means indicated by a block 19 into a quenching
time, i.e. the desired duration of supply of water onto
the coke, after which the valve 9 is again closed by
the command 22. The greater the measured maxim~n tem-
perature of the coke, the longer the quenching time
employed. The control signal 17 is proportional to the
average measurement signal 14, and is converted in means
indicated by a block 20 into a control signal for the
valve 10, so that with a high average measured tempera-
ture in the coke 3, the valve 10 is closed to a certain
degree, to achieve a desired average temperature setting
for the coke chamber walls.
The information from the signal 17 can also be
combined in means indicated by a block 20 with informa-
tion 25 obtained from a process computer 24, for pro-
cessing into a control program for the temperature
distribution in the burner chamber 7. Data can then
also be entered into the process computer 24 on coking
time, battery temperature and furnace charging.
It should be noted that the chambers in a coking
battery are emptied in succession, so that the command
23 must be routed to a different control valve or a
different burner chamber in each case.
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As explained above, a further refinement of the
systern is possible where meas~1re~ent signal 14
obtained as the car 2 passes the detector difers
significantly from -the standard pattern. This
indicates that the temperature distribution along
the quenching car and, consequently, usually over
the whole of a coking chamber, is irregular.
In this case, further comrnands can be ob-tained
from the block 20, to set individual burners or
groups of burners differently for each burner charnber
to achieve different amounts of heat applied at
different locations in the coking chamber.
It is also conceivable for the spray system
5 to be divided into sections, each being fed
separately by a supply pipe 11 with a control valve
9. Various signals 22 can then be conveyed from
the block 19 to each control valve 9 in such a way
that the various spray sections in the tower are
opened for differing periods, in dependence on the
2~ variation of the measurement signal from the detector
as the car 2 passes the detector.
