FIELD OF THE INVENTION
The present invention relates to an online system for tracking the positions /conditions of
rolling stock/slabs inside reheating furnace and a method for such tracking for controlled
heating with precise control on reheat temperature. More particularly, the present invention
relates to tracking of bloom/billet or slabs in double row, five zone, pusher type reheating
furnaces to heat the metal stock up-to desired level of temperature within permissible
accuracy for improving the steel plastic properties for further rolling. The system and
method of the present invention enable automatic control on resident time of the slab /
billet / bloom in each of furnace zone by monitoring steel stock conditions through
acquisition of online data relating to slab pusher and slab extractor signal from existing
motor control panel, such that if the slab is under-heated or overheated, necessary action is
implemented accordingly in zonal heating module. Importantly, all pusher and extractor
signals from all rows of all reheat furnaces are interfaced with a programmable logic
controller, reading the input signals through PLC and an algorithm developed to generate
position diagram for stocks inside furnace, enable display of graphical presentation of
process data, providing information to heating module and an event recorder for triggering
FEM module for execution of application program. The system and the method of the
present invention is thus capable of wide scale application for online data accusation and
analysis and control of heating of rolling stock based on position data inside reheat furnace.
The system and method thus ensure on one hand heating of stocks in different furnace
zones to achieve desired improved steel plastic property required for further processing
such as roughing/rolling and on the other hand an expert system based control of zonal
temperatures of furnace implemented through PLC based control system favour significant
saving of fuel gas consumption and particularly through programmed scheduling of furnace
temperatures during shutdown/repair period.
BACKGROUND ART
In the steel strip manufacturing process steel slabs obtained from continuous casting are
reheated up to temperatures of approximately 1250°C prior to the rolling process. The
required temperature at the end of such process has to be comprehended within a narrow
range determined by the subsequent on-line heat treatment process. Slab reheating in
pusher furnaces is one of the sources of variability that produce departures from that
narrow range. Every time a hot slab has to be discharged to be rolled, a new slab is

introduced into the furnace and the intermediate slabs are pushed sideways towards the
furnace outlet. The heating power is supplied by gas burners that use either natural gas or a
mixture of natural and coke gases and are arranged in several zones. Conventional
reheating comprise two preheating zones -an upper and a lower one , two heating zones -
an upper and a lower one, and one soaking zone are present. The burners of each zone are
controlled through thermocouple set points: a control loop regulates the air and gas flow
rates to match the set value with the temperature measured by a properly placed zone
thermocouple. Therefore, the problem of furnace temperature control is that of specifying
the set points that produce an adequate slab outlet temperature distribution. An infrared
pyrometer at the rougher is usually deployed to monitor the slab outlet temperature which
measures the slab longitudinal temperature profile on the upper side of the slab.
The slabs in plate mill are delivered from continuous caster. The length range of slabs is
around 5.6 to 10.2 m. These slabs are further cut to smaller plates by flame cutting
machines. As the plates are in cold condition, they cannot be rolled. In order to make them
susceptible for rolling, plates are heated in Reheating Furnaces. The heating in five zone
furnaces are divided in - Preheating zone (Top & Bottom), Heating Zone (Top & Bottom) and
Soaking Zone.
The plates are pushed one by one in the furnace from the charging side of furnace. These
plates move on water cooled skid pipes inside furnace. The skid pipes are cooled by
evaporating cooling system. The plates on the delivery side are pushed to pre-determined
position by pusher and then it is extracted by plate extractors. The plate extractors places
the plates on roll table from where it is send for roughing / rolling. Mixed gas (a mixture of
blast furnace gas and coke oven gas) of calorific value around 2500 KCal/m3 is used as fuel
gas. Air for combustion is supplied through natural draft. Air before reaching burners are
preheated in multi-cellular cross parallel flow type metallic recuperator.
In the conventional practice, slab tracking inside reheating furnace are done by
i) Laser barrier ELM/VRF , on the roll table with scanning HMD ROTA-SONDE DC . (
Make: M/s DELTA Sensors , M/s American sensors )
ii) For over 30 years ISD has provided CCTV system for imaging of slab inside
furnace and consequent image analysis. The 1ST - Ventus II water cooled camera
provides a clear view of the steel slabs progression through the furnace and the
burner performance. The cameras are mounted preferably near the exit of the

furnace on opposite sides above the product/ The combined view from 32
cameras provides a full 360° view.
Conventional laser and CCTV system suffers from disadvantages and limitations, which
include:
(a) Installation of this system in existing pusher type furnaces is very difficult.
Maintenance of such systems is also troublesome.
(b) Generally, these systems are not directly connected to on-line heating module for
on-line correction of zonal temperatures to get required slab temperature for rolling.
(c) There is no provision for storing of relevant information on pusher and extractor
operation, slab ID, last pushing time, entry time at heating zone, entry time at
soaking zone, time in furnace, no pushing in the shift, different zonal temperatures.
(d) Cost implication for the system is also one of the major adverse factor.
There has been therefore a need in the art to developing a system for online tracking of
rolling stock inside reheat furnace for desired on-line controlled heating module for on-line
correction of zonal temperatures to get required slab temperature for rolling based on
acquisition of slab pusher and slab extractor signal from existing motor control panel. Said
pusher and extractor signal of all rows of all furnaces are interfaced to Programmable Logic
Controller , said system adapted to reading the input signals through PLC , development of
algorithm for tracking of rolling stock and generating position diagram of rolling stock inside
the furnace , showing graphical representation of process data , providing information to
heating module and also as an event recorder for triggering FEM module for execution of
application program. The present system for online tracking of slabs in reheat furnace would
thus favour automatic controlled heating of slabs/billets/blooms to desired temperature to
suit steel plastic properties favoring flawless rolling/roughing downstream and on the other
hand eliminate wastage of fuel gas by introducing means for programmed scheduling of
furnace temperature, particularly during shutdown/repair period and thus making the
operation and maintenance of such systems simple, cost effective, productive and reliable
ensuring wide industrial application in steel industry.

OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to developing a system for online
slab tracking inside reheat furnace based on acquisition of slab pusher and slab extractor
signal from existing motor control panel for desired control of heating module for on-line
correction of zonal temperatures to get required slab temperature for rolling based on such
acquired signal data.
Another object of the present invention is directed to a system for online slab tracking inside
reheat furnace for desired control of heating module for on-line correction of zonal
temperatures tracking inside furnace wherein a PLC used to receive and interpret/read the
input pusher/extractor signals for tracking of rolling stock by using an algorithm.
A further object of the present invention is directed to a system for online slab tracking
inside reheat furnace for desired control of heating module for on-line correction of zonal
temperatures tracking inside furnace wherein said system and method favor the online
heating module to set zonal temperature so as to control the rolling stock temperatures.
A still further object of the present invention is directed to a system for online slab tracking
inside reheat furnace for desired control of heating module for on-line correction of zonal
temperatures tracking inside furnace wherein said system adapted to use an algorithm
developed to generate 'Valid' Push signal based on extractor and pusher 'On' signal
providing means for displaying the parameter values at any time and generating
information on performance improvement of the plant for management reporting.
A still further object of the present invention is directed to a system for online slab tracking
inside reheat furnace for desired control of heating module for on-line correction of zonal
temperatures tracking inside furnace wherein said system is adapted software enabled
operation to acquire and analyze the process data for the reheat furnace comprising digital
signals from pusher and extractor operation, slab ID, last pushing time, entry time at
heating zone, entry time at soaking zone, time in furnace, no pushing in the shift, different
zonal temperatures to favor tuning of the automatic controller to optimize zonal
temperatures.

A still further object of the present invention is directed to a system for online slab tracking
inside reheat furnace adapted for generating and displaying position diagram of rolling stock
of any reheat furnace,
A still further object of the present invention is directed to a system for online slab tracking
inside reheat furnace adapted for calculation and storing of resident heating time of all slabs
in different zones as well as guiding heating module for on-line setting and control of zone
temperatures.
A still further object of the present invention is directed to a system for online slab tracking
inside reheat furnace adapted to provide human-machine interface for indicating various
parameters for on-line implementation of corrective action.
A still further object of the present invention is directed to a system for online slab tracking
inside reheat furnace adapted for tracking of rolling stock as an event recorder for triggering
FEM module for execution of slab core and surface temperature prediction program.
A still further object of the present invention is directed to a system for online slab tracking
inside reheat furnace adapted for saving of wastage of fuel gases for the heating burners of
furnace by providing an expert system based programmed scheduling of furnace
temperature during shutdown/repair period as well as control on zonal temperatures
implemented through a PLC based system.
A still further object of the present invention is directed to a system for online slab tracking
inside reheat furnace adapted for analog and digital input output modules, making such
system simple accurate with prospects of wide application in reheating furnaces of steel
plants for desired control of slab temperatures by proper tracking of rolling stock inside
furnace.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is thus directed to a system for tracking of steel
stock/slabs inside reheat furnaces in plate mills adapted to ensure precise control of slab
temperature for roughing/rolling, comprising

means for acquiring slab pusher signal and slab extractor signal from motor control panel;
a programmable Logic Controller(PLC) operatively connected to receive and analyze the
said pusher signal and extractor signals ;
said PLC adapted for tracking rolling stock and also generating valid push signals based on
said extractor signal ;
means for displaying operating parameter values at anytime and generating information
including position diagram inside furnace using FEM module prediction of slab core
temperature.
According to another aspect of the present invention directed to said system for tracking of
steel stock/slabs inside reheat furnaces in plate mills, comprising
means to acquire slab pusher and slab extractor ON/OFF signal from respective motor
control panel;
a programmable Logic Controller(PLC) for reading the extractor and pusher signals from
field for generating Valid push signal for desired slab tracking inside furnace;
PC based system for graphical representation of process parameter data and generating
position diagram of rolling stock inside furnace;
'FEM' module for prediction of slab core temperature using finite element method;
online heating module to set zonal temperatures to control the rolling stock temperatures;
an expert system adapted for online control of zonal temperatures in bi-directional
communication with said PLC based system to operatively achieve desired predicted slab
temperature in furnace zones;
human-machine interface for indicating various parameters for initiating online action.

Also in said system for tracking of steel stock/slabs inside reheat furnace in plate mills, a
pair of CNBR cards are installed in said PLC system.
A further aspect of the present invention is directed to a system for tracking of steel
stock/slabs inside reheat furnace in plate mills, wherein said bi-directional communication
between the PLC system and the PC based system is established through Object Linking and
Embedding (OLE) for Process Control (OPC) which is a consortium of process control
vendors set up for inter application interfaces, using RS-Linx Professional as OPC sever.
A still further aspect of the present invention is directed to said system for tracking of steel
stock/slabs inside reheat furnace in plate mills, comprising said OLE for Process Control
(OPC), communicating between PLC system and PC based system, function in client-server
mode wherein OPC client is a program which requests server for data communication and
OPC server is a program which facilitates clients request by suitable data communication.
According to yet another aspect of the present invention directed to said system for tracking
of steel stock/slabs inside reheat furnace in plate mills wherein said data communication
between server and client can be either synchronous or asynchronous.
Another advantageous aspect of the present invention directed to said system for tracking
of steel stock/slabs inside reheat furnace in plate mills, wherein said PLC system is adapted
with analog and digital input-output modules making the system simple yet accurate.
A still further aspect of the present invention is directed to a system for tracking of steel
stock/slabs inside reheat furnace in plate mills, wherein the zonal temperatures of furnace is
set by online heating model and the set temperatures are downloaded to PLC for control of
air/gas for achieving said model calculated zonal set temperatures.
According to yet another aspect of the present invention directed to a method for tracking
of steel stock/slabs inside reheat furnace in plate mills for precise control of slab
temperature for roughing/rolling using the above described system, comprising
collecting pusher and extractor motor 'ON', 'OFF' signal from motor control panel through
PLC using a developed algorithm;

displaying the parameter values online at any time on performance of plant;
generating and displaying position diagram of rolling stock of reheat furnace;
determining and storing of information on resident heating time of slabs in different zones
of reheat furnace;
guiding heating module for online setting and control of zone temperatures;
taking online action by input through human machine interface based on indicated
parameter values;
tracking of rolling stock as an event recorder for triggering FEM module for execution of slab
core and surface temperature prediction;
setting zonal set temperatures by online heating model, downloading the set temperatures
to PLC for control of air/gas for burners in different zones to attain the set temperatures;
generating 'Valid' push signal based on extractor and pusher "ON" signal such that pusher
operation is effected within specified time gap, preferably about 85 seconds of respective
extractor operation; and
optimizing burner operation, during operation/shutdown of the reheat furnace.
The present invention and its objects and advantages are described in greater details with
reference to the following non limiting illustrative drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1: is the schematic illustration of the conventional 5-zone pusher type reheat
furnace of plate mill of a steel plant.

Figure 2: is the schematic cross-sectional view of an existing five zone reheating furnace
showing the different zones inside the furnace.
Figure 3: is the illustration of scheme for Level-II and OPC server connection according to
the tracking slab positions and online heating/temperature monitoring system of the present
invention.
Figure 4: is the schematic illustration of the soaking zone air-gas control using delay model
according to the system of the present invention.
Figure 5: is the illustration of flow chart for generating valid push signal using the system
of the invention.
Figure 6: is the schematic illustration of the online slab tracking system of plate mill in
steel plant wherein extractor and pusher operation along with valid push signal has been
shown.
Figure 7: is the schematic illustration of the online slab tracking system of plate mill in
steel plant showing graphical representation of relevant information on pusher and extractor
operation , slab ID , last pushing time , entry time at heating zone , entry time at soaking
zone , time in furnace , no pushing in the shift and also the different zonal temperatures .
Figure 8: is the illustration of scheme for Signal tapings from Motor control panel (ECR#1)
for pusher .
Figure 9: is the illustration of scheme for Signal tapings from Motor control panel (ECR#2)
for extractor.
Figure 10: is the illustration of connection of pusher & extractor signals from Main TB in
Motor Control Panel room to Main fused TB in Reheat Furnace Control room.
Figure 11: is the illustration of the connection of pusher and extractor signals to PLC
showing the final termination plan in respective PLC panels.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING FIGURES
The present invention is directed to providing a system for online slab tracking inside reheat
furnace based on acquisition of slab pusher and slab extractor signal from existing motor
control panel for desired control of heating module for on-line correction of zonal
temperatures to heat the metal stock up to desired level of temperature within permissible
accuracy in order to achieve slab temperature with improved steel plastic properties
required for roughing/rolling at stages further downstream.
Reference is first invited to accompanying Figure 1, that illustrate schematically the general
layout of Plate Mill in one of the Steel Plant of the applicants showing the location of 3
reheat furnaces. Each furnace has two rows for slab pushing. Hot slabs from 6 rows are fed
to roughing stand for rolling. From roughing mill, the material move to finishing mill for
further rolling.
Reheating furnaces play a crucial role in hot rolling mills, in which semi-finished steel (in the
form of blooms, billets or slabs) are heated to an elevated temperature for improving the
steel plastic properties, which make it susceptible for rolling. The basic requirement of
Reheating Furnace is to heat the metal stock up-to desired level of temperature within
permissible accuracy. That is why tracking of billets / slabs/ blooms are very much essential
to know whether the individual item of stock is properly heated or not. If the rolling stock
position is known, then automatically resident time of the slab / billet / bloom in each and
every zone can be calculated. If the slab is under heated or overheated, necessary action is
taken accordingly in zonal heating module.
Reference is now invited to the accompanying Figure 2 that illustrate the cross sectional
view of 5-zone reheating furnace comprising preheating zone (Top and Bottom), heating
zone (Top and Bottom) and soaking zone. Air and mixed gas (blast furnace and coke oven
gas) are used as fuel for lighting the burners. The ratio of air and mixed gas are controlled
by PID controllers to achieve desired zonal temperatures and slab temperatures.
The PLC based on-line slab tracking system according to the present invention comprising
the following hardware components:

i) Programmable Logic Controller adapted to read the signals from field e.g. pusher
and extractor signals, wherein an software programme is provided for valid push
signal.
ii) PC based Level-II system for graphical representation of process data and
generating position diagram for rolling stock inside the reheat furnace.
In order to know the exact position of any slab/billet/bloom with stock temperature at any
moment of time. For this purpose, pusher signals from motor control panel (ECR # 1) and
extractor signals (ECR # 2) have been connected to PLC (Programmable Logic Controller).
The input signals are read in PLC and an algorithm for tracking of rolling stock have been
made and a software programme for valid push signal have been developed and provided.
This favors the on-line heating module to set zonal temperatures which in turn control the
rolling stock temperature. Advantageously, the system of the invention further favors
storing of relevant information on pusher and extractor operation, slab ID, last pushing time
, entry time at heating zone , entry time at soaking zone , time in furnace , no pushing in
the shift , different zonal temperatures. The improved tracking system according to the
present invention is adapted for analog and digital input-output modules, making the
system simple yet accurate and having wide application in all reheating furnaces of steel
plants for desired control slab temperature by proper tracking of rolling stock inside furnace.
Reference is now invited to the accompanying Figure 3 illustrates the block diagrammatic
representation of OPC (OLE for Process Control) based communication between PLC and PC
based level-II system. PLC program is developed to get valid push signal from extractor and
pusher movements, and whose analysis are done in Level-II computer system.
The configuration and functional aspects of the hardware components of the PLC based
automatic system according to a preferred embodiment of the present invention for
implementing slab tracking system for temperature control of zones/slab in reheat furnace
are as described below:

PLC based Control System
In one of the plate mill of the applicants where the system of the invention is introduced in
5 zone reheat furnace, comprised of three pusher type re-heating furnaces. Furnace # 1
and Furnace#3 are controlled by Allen Bradley make dual redundant control net processor
1756-L55M13 installed therein. All the I/O's of RF#1 & RF#3 are connected to Allen Bradley
make Flex Logix I/O cards. The processor and I/O cards are connected vide dual redundant
control-net data highway. However, RF #2 is controlled by single loop controller and a part
of analog and digital I/O's for RF#2 are connected to Flex I/O for display purpose only. The
I/O systems for three furnaces are mounted in three different panels in heating control
room. In order to connect all the I/O's of RF#2 to existing PLC system, the same has been
upgraded by some additional flex logix cards and PLC processor accessories. These cards
have been mounted on the existing panel meant for RF#2 after modification in panel wiring.
In order to incorporate additional I/O's and PLC program, the memory of existing processor
has been enhanced to 3.5 MB and a pair of CNBR cards are installed. This new PLC system
is interfaced with PLC system of RHF 1 & 3. The signals from newly installed instrumentation
such as flow / temperature transmitters, digital indicators, A/M stations, square root
extractors, alarm annunciation system etc. have been interfaced with PLC I/O cards.
The upgraded PLC system used in the slab tracking system according to the invention thus
comprised the following accessories :



Level - II Computer System:
A Level - II computer system is installed for supervisory model and FEM package. For bi-
directional communication between said computer system and aforesaid PLC system
following interface card and communication cable used to implement this tracking system.

The specification of Level - II computer used in the slab tracking and online process control
system is as follows :



In addition to above an OPC server software is introduced which links model and FEM
package with PLC system. Communication between Level-II model and PLC has been
established through OPC (Object Linking and Embedding for Process Control). OPC is a
consortium of process control vendors and has been set up for inter application interfaces.
OPC is based on concept of OLE (Object Linking and Embedding), which is a Microsoft
technology for inter application interfaces. At the heart of OLE is COM (Component Object
Model), which is a binary standard that specifies how OLE component interacts with each
other. COM is a language independent standard. OPC functions in client - server mode. An
OPC client is a program, which requests server for data communication. Similarly, OPC
server is a program which facilitates clients request by suitable data communication. The
data communication between server and client can be either synchronous or asynchronous.
RS-Linx Professional is OPC Server provided by Rockwell Automation. A special OPC client
software has been developed for bi-directional communication between Level - II and
Rockwell PLC. The communication between PLC and Level - II using RS-Linx OPC server is
shown in accompanying Figure 3.
Microsoft Access is used as database for Level -II and FEM application. For the aforesaid
software development following software packages have been incorporated.


Furnace control program:
The basic furnace control program has been developed in PLC using ladder logic and
function block diagram. The program contains different software modules for individual
furnace zone temperature control.
The accompanying Figure 4, illustrates the trend of soaking zone temperature for Reheat
Furnace # 1. The zonal temperature is set by on-line heating model and the set
temperature is downloaded to PLC (Programmable Logic Controller) for control of air/gas.
The picture shows that process temperature follows the model calculated temperature.
Logical mapping Module
This module logically calculates the position of different slabs in a row of heating based on
the input data of pushing time, slab size (width) and furnace dimensions. Accordingly, it
sends the environment temperature history of a particular slab to the FEM calculations. A
graphical user interface (GUI) has been developed which shows temperature at different
locations of a slab.
Reference is next invited to the accompanying Figure 5 that represents flow chart from
screenshot of the program which detects a valid pushing signal based on the signals of
pusher and extractor. It has been observed that if the pusher operates within 85 seconds of
respective extractor operation, then it is considered that a valid push signal has occurred.

Accompanying Figure 6 shows the timing of extractor and pusher operation along with
valid push signal with the respective signals plotted on time scale to show that valid push
signal correspond to pusher action within 85 seconds of the respective extractor on
operation.
Accompanying Figure 7 shows the screenshot for thermal mapping module that logically
calculate the position of a slab with ID in a row of heating in furnace based on input data of
pushing time, entry time at heating zone, entry time at soaking zone, time in furnace, slab
size and furnace dimensions for FEM calculations for locating a slab in reheat furnace.
Accompanying Figure 8 shows signal tappings from pusher from motor control panel
wherein the pushing signals have been tapped from auxiliary contacts of FX1 of respective
motor control panel. It may be noted that P16A, P16B, P22A, P22B, P28A & P28B stand for
pushing signals tapped from respective panel's Auxiliary Contacts of FX1 (Potential free
Contacts). 24 V is coming from respective PLC I/O Panels for FCE#1,2 & 3 of PLC Control
Room.
Accompanying Figure 9 shows the details of signal tappings for extractors from the Motor
control panel. Extractor signals have been tapped from auxiliary contacts of panel 35 and 45
of ECR# 2(electrical control room).
Accompanying Figure 10 shows the connection of pusher and extractor signals from Main
TB in Motor Control Panel room to Main fused TB in Reheat Furnace Control room.
Accompanying Figure 11 shows the connection of pusher and extractor signals to PLC. The
final termination plan in respective PLC panel has been shown wherein respective signals
are coming from Main Fused TB of RHF Control Room.
It is thus possible by way of the present invention to providing a system for online slab
tracking in reheat furnace in plate mills of steel plants for desired heating and temperature
control to achieve desired slab temperature required for improved steel slab plastic property
for further roughing/rolling operation. The tracking and online temperature control is
achieved through PLC based control implemented by an algorithm for generation of Valid
push signal based on extractor and pusher "ON" signal and PC based level II system for

graphical presentation of process parameter values at any time and generating position
diagram of rolling stock inside furnace as well as providing information on performance
improvement of the plant for management reporting, as necessary. The improved tracking
system according to the present invention is adapted with analog and digital input-output
modules, making the system simple yet accurate and thus capable of wide application in all
reheating furnaces of steel plants for desired slab temperature control by proper tracking of
rolling stock inside furnace and online control of zonal temperatures of furnace.

We Claim:
l.A system for tracking of steel stock/slabs inside reheat furnaces in plate mills adapted to
ensure precise control of slab temperature for roughing/rolling, comprising
means for acquiring slab pusher signal and slab extractor signal from motor control panel;
a programmable Logic Controller(PLC) operatively connected to receive and analyze the
said pusher signal and extractor signals ;
said PLC adapted for tracking rolling stock and also generating valid push signals based on
said extractor signal ;
means for displaying operating parameter values at anytime and generating information
including position diagram inside furnace using FEM module prediction of slab core
temperature.
2. A system for tracking of steel stock/slabs inside reheat furnaces in plate mills as claimed
in claim 1, comprising
means to acquire slab pusher and slab extractor ON/OFF signal from respective motor
control panel;
a programmable Logic Controller(PLC) for reading the extractor and pusher signals from
field for generating Valid push signal for desired slab tracking inside furnace;
PC based system for graphical representation of process parameter data and generating
position diagram of rolling stock inside furnace;
'FEM' module for prediction of slab core temperature using finite element method;
online heating module to set zonal temperatures to control the rolling stock temperatures;
an expert system adapted for online control of zonal temperatures in bi-directional
communication with said PLC based system to operatively achieve desired predicted slab
temperature in furnace zones;

human-machine interface for indicating various parameters for initiating online action.
3. A system for tracking of steel stock/slabs inside reheat furnace in plate mills as claimed
in claims 1 or 2, wherein a pair of CNBR cards are installed in said PLC system.
4. A system for tracking of steel stock/slabs inside reheat furnace in plate mills as claimed
in anyone of claims 1 to 3, wherein said bi-directional communication between the PLC
system and the PC based system is established through Object Linking and Embedding
(OLE) for Process Control (OPC) which is a consortium of process control vendors set up for
inter application interfaces, using RS-Linx Professional as OPC sever.
5. A system for tracking of steel stock/slabs inside reheat furnace in plate mills as claimed
in anyone of claims 1 to 4, comprising said OLE for Process Control (OPC), communicating
between PLC system and PC based system, function in client-server mode wherein OPC
client is a program which requests server for data communication and OPC server is a
program which facilitates clients request by suitable data communication.
6. A system for tracking of steel stock/slabs inside reheat furnace in plate mills as claimed
in anyone of claims 1 to 5, wherein said data communication between server and client can
be either synchronous or asynchronous.
7. A system for tracking of steel stock/slabs inside reheat furnace in plate mills as claimed
in anyone of claims 1 to 6, wherein said PLC system is adapted with analog and digital
input-output modules making the system simple yet accurate.
8. A system for tracking of steel stock/slabs inside reheat furnace in plate mills as claimed
in anyone of claims 1 to 7, wherein the zonal temperatures of furnace is set by online
heating model and the set temperatures are downloaded to PLC for control of air/gas for
achieving said model calculated zonal set temperatures.
9. A method for tracking of steel stock/slabs inside reheat furnace in plate mills for precise
control of slab temperature for roughing/rolling using the system as claimed in claims 1 to
8, comprising

collecting pusher and extractor motor 'ON', 'OFF' signal from motor control panel through
PLC using a developed algorithm;
displaying the parameter values online at any time on performance of plant;
generating and displaying position diagram of rolling stock of reheat furnace;
determining and storing of information on resident heating time of slabs in different zones
of reheat furnace;
guiding heating module for online setting and control of zone temperatures;
taking online action by input through human machine interface based on indicated
parameter values;
tracking of rolling stock as an event recorder for triggering FEM module for execution of slab
core and surface temperature prediction;
setting zonal set temperatures by online heating model, downloading the set temperatures
to PLC for control of air/gas for burners in different zones to attain the set temperatures;
generating 'Valid' push signal based on extractor and pusher "ON" signal such that pusher
operation is effected within specified time gap, preferably about 85 seconds of respective
extractor operation; and
optimizing burner operation, during operation/shutdown of the reheat furnace.
10. A system for tracking of steel stock/slabs inside reheat furnace in plate mills for precise
control of slab temperature for roughing/rolling and a method for its implementation
substantially as herein described with reference to the accompanying drawings.

A system for tracking the positions of rolling stock/slabs inside reheating furnace and a
method for precise control on reheat temperature, particularly, for tracking of bloom/billet
/slabs in double row, five zone, pusher type reheating furnaces to heat the metal stock
within permissible accuracy to favor for further roughing/rolling. The system enable
automatic control on resident time of the slabs in each furnace zone by monitoring steel
stock conditions through acquisition of online data. All pusher and extractor signals are
interfaced with a programmable logic controller (PLC), which read the input signals and
generate position diagram for stocks inside furnace using an algorithm, enable display of
graphical presentation of process data, providing information to heating module and an
event recorder for triggering FEM module for execution of application program in
communication with a PC based expert system. The system and the method is thus capable
of wide scale application for steel stock heating based on position/process data inside reheat
furnace and also favour significant saving of fuel gas consumption.