FIELD OF THE INVENTION
The present invention relates to a control system adapted for
controlling heat in coke oven battery. Particularly, the
invention is concerned about a system for on-line heating
control in coke oven batteries by extending and adjusting
heating pause time.
BACKGROUND AND THE PRIOR ART
At present battery heating control is through manual
adjustment of thermal regime based on battery pushing
schedule. In some automatic heating control, heat demand is
always considered the same for all the ovens. Average
temperature of heating wall is measured by manual measurement
of few selected vertical flues with hand held optical
pyrometer. This method of measurement is labour intensive,
subjective and does not always co-relate well with coke
temperature inside the oven. Some of the systems are based on
coke mass temperature but does not take care of coking index.
Other systems are based on regenerator top temperature and
does not take care of actual coke temperature or coking index.
The total software and hardware in such system are imported
and indigenous know-how is not available.
Some control systems are based on direct regulation of heating
gas flow and battery draft. However these systems suffer from
one drawback that actual battery thermal regimes are changed
at every reversal, which sometime disturbs the battery
regulation. Moreover these systems are not applicable in sub-
batteries having common chimney.

The manual control system is not based on actual process
condition and heat demand calculations but depends on the
experience of shop operators. Hence it is not accurate and
utilises more energy. Also as there is no check for coke mass
temperature and actual progress of carbonisation, the quality
of coke is inferior and inconsistent. Even the automatic
control systems commercially available in the market are
either feedback or feed-forward in nature. But to achieve
optimum battery performance, it is essential to have both
feed-forward (Heat Demand) and feed-back (coke mass
temperature and coking index).
US 4,003,803 discloses a control system for preventing an
excessive temperature rise within the heating flues of a
battery of coke ovens. The system comprises a controller and a
clocking circuit along with a computer for each one of the
coke oven chambers. In the system a first control signal is
responsive to the occurrence of charging coal into a given
oven chamber and starts the clock. A second control signal is
responsive to the pushing of coke from the oven chamber and
stops the clock. When the duration of the coking time for a
given oven chamber exceeds a predetermined coking time, the
controller provides a signal for operating valves to terminate
the flow of combustion gases into heating flues at the sides
of that coke oven chamber. In the system, the computer updates
coking time and establishes from time-to-time from data fed to
it, the thermal state of each heating flue in the battery. It
was not known from the prior art that by way of appropriate
data acquisition system comprising of proper control system
and mathematical model pause time can be suitably extended and
adjusted for controlling and modifying the flow of heat in the
coke batteries.

CN 100460760 C discloses a heat value of a mixed gas stability
control system and computer control model of technical solutions
where the blast furnace gas input pipe is equipped with blast
furnace gas pressure regulating valves, blast furnace gas
pressure sensors, flow sensors blast furnace gas and blast
furnace gas flow control valve; in the coke oven gas input pipe
is equipped with a flow sensor and coke oven gas gas flow
control valve; in the mixed gas export pipeline is equipped with
mixed gas calorific value of the gas pressure sensor and hybrid
sensor; addition, there is a computer-controlled device and
blast furnace gas input pipe blast furnace gas pressure
regulating valve, blast furnace gas pressure sensors, blast
furnace gas flow sensor and blast furnace gas flow control
valve, and coke oven gas input pipe flow sensor on the coke oven
gas and coke oven gas flow control valve, and mixed gas export
pipeline on the calorific value of the gas mixture and mixed gas
sensor electrically connected to a pressure sensor.
None of the prior art documents as discussed above teaches that
by way of appropriate data acquisition system comprising of
proper control system and mathematical model pause time can be
suitably extended and adjusted for controlling and modifying the
flow of heat in the coke batteries. It was also not known from
the prior art that heating pause time control can be applied in
controlling heat input to the battery by way of using actual
Coke Mass Temperature and Coking index as feedback control while
a prediction of mathematical model as feed-forward control.
Thus there is a need to provide for a system for on-line heating
control in coke oven batteries by extending and adjusting
heating pause time.

The present inventors have found that the on-line heating
control in coke oven batteries is possible by data acquisition
through PLC system and control of battery heating by adjustment
of pause time calculated by a mathematical model. This system
can be implemented in any coke oven having similar heating
system.
The present invention further discloses the application of
heating pause time control in controlling heat input to the
battery by way of using actual Coke Mass Temperature and Coking
index as feedback control while a prediction of mathematical
model as feed-forward control.
It also teaches the application of computer hardware, software
and PLC.
OBJECTS OF THE INVENTION
Accordingly, one object of the present invention is to provide a
control system for on-line heating control of coke oven battery
through a data acquisition system.
Another object of the present invention is to provide such data
acquisition system which is based on Programmable and Logic
Controller.
Yet another object of the present invention is to introduce
variable heating pause time for said control system.

SUMMARY OF THE INVENTION
According to one aspect of the present invention there is
provided a heat control system for controlling heating of coke
oven batteries, said system comprising plurality of modules
which comprises:
first module having plural sensing means operatively mounted
on said oven batteries so as to sense various process
parameters thereafter communicating acquired parametric
data/information to second module; said second module
comprising means for receiving said data/information from
said first module,
wherein said means for receiving data/information is adapted
to control battery heating by means of adjusting pause time
wherein said pause time being processed by a mathematical
model located in a third module which is in operative
connection with the second module.
According to another aspect of the present invention there is
provided a method for controlling heat in coke oven batteries,
said method comprising steps of:
sensing various process parameters by means of first module
having plural sensing means operatively mounted on said oven
batteries thereafter communicating acquired parametric
data/information to a second module;
receiving of said data / information by said second module
wherein said received data/information is adapted to control
battery heating by means of adjusting pause time wherein said
pause time being processed by a mathematical model located in

a third module which is in operative connection with the
second module.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is implemented in a coke oven twin flue
underjet type heating System. The Battery is divided in two
blocks A and B each having 39 ovens. Each oven is 4.45 meter
tall, 13 meter in length and 400mm wide with a coal charge
capacity of around 17 tons/oven. Each oven is sandwiched
between two heating walls. There are 28 vertical flues in each
heating wall. Either Coke Oven (CO) gas or Blast Furnace (BF)
gas is burnt inside the vertical flues. There is a common flue
gas chimney located at one end of battery which caters to both
the heating blocks.
Coal is charged inside the oven from oven top after closing
both side doors and coal is heated in absence of air by the
heat transferred from heating wall. During coking, raw CO gas
is generated inside the oven which escapes through ascension
pipes and collecting main to the exhauster house. After a
certain period of time, called Coking Period, coal is
converted into coke which is pushed out to the quenching car
and taken to quenching tower for quenching with water.
Quenched coke is sent to Blast Furnace for production of hot
metal.
The optimum heating control is one of the crucial operations,
which delineate the entire coal carbonization process in Coke
Oven Battery. Optimum heating control by way of ensuring
complete combustion, minimizing sensible heat being taken away
by the waste gas and reducing heating time schedule has a
crucial role in lowering the energy inputs and improving the

coke quality. Meticulous control of heating requires knowledge
about heating gas, waste gas and distillation gas chemical
composition, coke mass temperature, different phases of
carbonisation, coal-coke properties etc. This invention
exemplifies a stupendous in-house effort in terms of
marshalling multidisciplinary resources in the fields of heat
transfer & combustion, kinetics, reaction dynamics of
carbonisation process, control system, sensors and the three
levels of automation with intricate mathematical modelling.
The invention is based on hierarchical automation design
system comprising plurality of modules. The modules comprises
first module (level 0) which has plural sensing means. The
sensing means comprises thermocouples, temperature
transmitters, infra red pyrometer, bus bar sensor and infra
red sensor and combinations thereof. The sensed data is
received by means for receiving data / information which
comprises advanced Programmable & Logic Controller (PLC) and
Human Machine Interface (HMI) comprising the second module
(Level-1). The third module comprises mathematical model
(Level-2) automation. The mathematical model is based on the
philosophy of continuous supply of heat to battery as per
actual process demand.
Coking index is estimated by measuring raw gas (distillation
gas) temperature at the base of ascension pipe. The signature
analysis of raw gas temperature reveals an initial increasing
trend with the progress of carbonization till a maximum peak
is reached and then drops abruptly. The peak temperature
signifies the time at which coke layers meet at the center of
oven where coal carbonization has completed with the removal
of volatile matters. Coking index is the ratio of total coking
period and time to reach the peak. This is an index of coke

readiness and gives the progress status of coal carbonization
in the battery.
The instrumentation system also records process parameters
like tunnel temperature, heating gas flow / pressure, battery
draught etc, pushing / charging current etc.
The third module (Level-2 Automation) is based on meticulously
worked out mass balance equations. The total heat energy
imparted in the battery by combustion of heating gas is mainly
consumed by following components:
Coal - Coke Carbonization process.
Product of coal distillation like benzol, tar,
moisture etc.
Heat loss through Waste gas.
Heat loss through surface radiation.
The system works by perfect symbiosis between calculated
theoretical heat demand and actual heat consumed. At every
winch reversal, the system calculates the actual heat consumed
in last reversal and net cumulative heat consumed by the ovens
till its pushing. Based on this model calculates remaining
heat to be given to each oven and heat requirement of each
oven for next reversal. From this the model calculates the
actual heat demand of the battery for the next reversal. The
thermal regime of the battery is calculated from actual heat
demand in terms of heating gas flow and pressure. However, the
calculated heating gas flow is compensated with two feedback
signals. First compensation is done w.r.t. actual coke mass
temperature to integrate the thermal condition of battery. The
second compensation is done w.r.t. coking index, which

represents the coke readiness of the battery. The battery-
thermal regime is thus compensated both w.r.t. actual battery
thermal condition as well as coke readiness.
The actual control of battery heating is achieved by adjusting
the heating pause time. Pause time is the time between two gas
reversals when both the flow of gas and air is stopped for a
moment. The calculated pause time is downloaded to PLC system,
which interacts with battery winch reversal electrical
mechanism to introduce additional heating pause time.
In addition to prediction and control of battery heating, the
system generates many HMI screens for convenience of battery
operation and analysis of battery health conditions. Some
salient features has been described below:
Oven Pushing & Charging status and actual coking time
display.
Oven-wise display of actual coke mass temperature
profile.
Oven-wise display of actual pushing and charging force
profile.
Oven-wise display of coking index.
Display of winch reversal times.
Alarm generation in the event of winch reversal failure.
In the method of the present invention for controlling heat in
coke oven batteries various process parameters are sensed by
means of first module having plural sensors. The parametric
data is then communicated to a second module where the data is
received and is processed with reference to some pre-feed
data. The compared data is then fed to the mathematical model
where the actual heat consumed by the batteries is calculated.
Based on the calculated actual heated consumed, heating pause

time is decided and adjusted, and fed to the PLC which
interacts with battery winch reversal electrical mechanism.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 shows the sequence of events in a winch reversal
mechanism for pause control is illustrated.
Figure 2 shows the block schematic of control system.
Figure 3 shows the schematic of Oven identification Sensors
installed at Coke Oven Battery No. 1 of DSP (C0B1-DSP).
Figure 4 shows the computer screen predicting Heating Gas Flow
and Pause Time as predicted by Model.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Heating control in a coke oven battery is generally
accomplished by directly controlling fuel gas flow and battery
draft. However, in the aforesaid type of Coke Ovens this
method of heat input control is not possible. This is because
each sub-battery is heated by a different fuel - either coke
oven gas or blast furnace gas but since the chimney is located
at one end of the battery, the draught is common to both the
sub-batteries. This gives rise to a unique situation that if
say, as per model calculation the coke oven gas pressure and
consequently the draught is adjusted in block A, the draught
in block B also changes and disturbs the heating in that
block.
Hence a different methodology has been adopted through which
actual heat input control to the battery is regulated by

manipulating the duration of flow of heating gas. This is done
by pause time control during winch reversal. Pause time is the
time between two gas reversals when both the flow of gas and
air is stopped for a moment.
Figure 1 illustrates the sequence of events in a winch
reversal mechanism for pause control. Initially gas cock of
one side is closed followed by air purge. Then air flappers of
the same side closes. This is the time when flow of both gas
and air ceases in the battery. This is called Heating Pause.
In normal sequence it takes place only for few second. However
the control system of the present invention extends and
adjusts this pause time to control the heat input to the
battery. After completion of heating pause, air flappers of
other side opens followed by gas cock opening of other side.
This completes one reversal cycle.
Figure 2 shows the block schematic of said control system. The
system comprises of modules which comprises first module (Ml)
(level 0) having plural sensing means operatively mounted on
said oven batteries so as to sense various process parameters
thereafter communicating acquired parametric data/information
to second module (M2); second module (level 1) comprising
means for receiving said data/information from said first
module, said means for receiving data/information adapted to
control battery heating by means of adjusting pause time
wherein said pause time being processed by a mathematical
model located in a third module (M3) (level 2) which is in
operative connection with the second module (M2).
The instrumentation block in first module comprises of
thermocouples (1), temperature transmitters (2), infra red
pyrometer (3), bus bar sensor (4), infra red oven
identification sensors (5) and winch reversal mechanism (6).

The second module (M2) comprises of a Human machine interface
(7) and a programmable and logic controller (8).
The system is both feed-forward as well as feedback in nature.
Initiating feed-forward action, the third module comprising of
the model (9) calculates the heat demand of an oven as soon as
it is charged with coal. The system incorporates feedback
corrections with respect to final coke mass temperature and
actual coking index.
Meticulous prediction of battery thermal regime requires a
precise knowledge about several process parameters like coke
mass temperature, coking index, charging time, pushing time,
waste gas temperature, coal moisture, heating gas calorific
value, heating gas / waste gas / distillation gas chemical
analysis etc. The present invention incorporates an efficient
Instrumentation system to facilitate PLC and Mathematical
Model with process information.
Figure 3 shows the schematic of oven identification sensors as
mounted in Coke Oven Battery No. 1 of DSP. Oven Pushing and
Charging time is recorded by a series of Infrared Sensors.
Infrared receivers for leveling comprises receivers IRLI, IRL2/
IRL3, IRLI78/ IRLH (n = 1/2,3, ) are mounted near the
base of individual ovens, while transmitters for pushing
comprises IRpj., IRp2, IRp3 IRpi78 IRPn (n = 1,2,3, ) are
mounted in pusher car (10) . The pusher car (10) comprises
leveler transmitters (11) and pusher transmitters (12) . During
oven pushing operation, the respective IR transmitter gets
power and corresponding IR receiver gets activated. Similarly,
during leveling operation, the corresponding IR transmitter -
receiver pair gets activated. All the IR receivers are
connected to PLC system. A PLC based software records the

time, whenever a receiver is switched from low to high. The
software also designate the recorded time as pushing or
charging time of a particular oven.
Figure 4 shows the computer screen predicting Heating Gas Flow
and Pause Time as predicted by Model. The PLC system is
envisaged through a network of PLC's and one HMI workstation.
The process model is implemented in a high end personal
computer. The model software is written in VC++ (Microsoft
Visual Studio.Net). The bidirectional data communication
between VC++ and PLC has been achieved through an OPC OLE for
Process Control) client software developed in VC++ and is an
integral part of model. SIMATIC-NET has been used as OPC
server. At every winch reversal, the model reads all the
process related data from PLC and calculates heating pause
time for next reversal. It immediately downloads the
calculated pause time to PLC, which actually controls the
winch reversal mechanism.

WE CLAIM
1. A heat control system for controlling heating of coke
oven batteries, said system comprising plurality of
modules which comprises:
first module having plural sensing means operatively
mounted on said oven batteries so as to sense various
process parameters thereafter communicating acquired
parametric data/information to second module;
said second module comprising means for receiving said
data / information from said first module,
wherein said means for receiving data/information is
adapted to control battery heating by means of adjusting
pause time wherein said pause time being processed by a
mathematical model located in a third module which is in
operative connection with the second module.
2. System as claimed in claim 1 wherein sensing means
selectively comprises thermocouples, temperature
transmitters, infra red pyrometer, bus bar current
sensor, infra red oven identification sensor and
combination thereof.
3. System as claimed in claim 1 wherein said means for
receiving data / information comprises programmable logic
Controller (PLC).

4. System as claimed in claim 1 further comprises means for
human machine interface (HMI).
5. System as claimed in claim 4 wherein said means being
adapted for displaying oven and/or oven wise pushing and
charging time profile.
6. System as claimed in claim 4 wherein said means being
adapted for displaying oven and/or oven wise pushing and
charging force profile.
7. System as claimed in claim 1 wherein said mathematical
model (ix) is adapted to determine actual heat consumed
in the last winch reversal.
8. A method for controlling heat in coke oven batteries,
said method comprising steps of:
sensing various process parameters by means of first
module having plural sensing means operatively mounted on
said oven batteries thereafter communicating acquired
parametric data/information to a second module;
receiving of said data / information by said second
module wherein said received data/information is adapted
to control battery heating by means of adjusting pause
time wherein said pause time being processed by a
mathematical model located in a third module which is in
operative connection with the second module.

9. Method as claimed in claim 8 wherein heating gas flow is
compensated selectively by actual coke mass temperature
and/or coking index and/or combinations thereof.
10. Method as claimed in claims 8 and 9 wherein pause time
being fed to PLC so as to establish its interaction with
the battery winch reversal mechanism to introduce
additional heating pause time.

ABSTRACT

TITLE : A COMPUTERIZED COKE OVEN HEATING CONTROL SYSTEM
USING HEATING PAUSE TIME CONTROL TECHNIQUE
The present invention relates to a control system adapted
for controlling heat in coke oven battery. The system
comprises plurality of modules, which includes first module
(Ml) having plural sensing means (4,5) operatively mounted
on the oven batteries for sensing various process
parameters. The acquired parametric data/information is
communicated to second module (M2) comprising means for
receiving the data/information from the first module (Ml) .
The system further comprises a third module (M3), which is
in operative connection with the second module (M2). The
invention also relates to a method for controlling heat in
coke oven batteries.