FIELD OF THE INVENTION
The present invention relates to an automatic control system for raw material
charging conveyors for blast furnace. More particularly, the present invention relates
to a PLC and position sensors based automatic control system to reduce the delay
due to manual start up of charging section, which is implemented in an integrated
manner so that the series of conveyors in a section can be started automatically in
sequence if the healthy conditions for start are met. Importantly, inductive position
sensors have been introduced in trolleys of the conveyor to sense the start position.
Section start and stop logic have been developed and incorporated with the existing
electric and safety interlocks so that all charging section can be started automatically
with a push of a button in dispatcher room. The auto control system for raw material
charging in blast furnaces according to the present invention thus favour starting of
a section from a single location and by a single push of a button thus reducing
manual delays.
BACKGROUND ART
Each charging section comprises of a series of conveyors to feed raw material to
bunkers of different blast furnaces. In conventional method of charging blast
furnaces, raw material is fed to bunker of a particular blast furnace, a series of
sequential start up operation for each conveyor is carried out by different operators
stationed in different shuttle floor of each blast furnace. A good co-ordination is
required by all operators so that the entire section can be started manually. Each
manual start of the section requires minimum 30 minutes as the section start
operation for conveyors is distributed over large area and involves different
operators.
To start the charging line, a sequence of start operation conventionally required to
be done by a number of operators positioned far off from each other resulting in
large section startup time.
There has been thus a persistent need in the related filed to developing a system for
automatic start/stop switching in desired sequence free of any manual intervention
and resulting delay, so that all charging section can be started automatically with a
push of a button in dispatcher room to start and stop a chain of conveyors from
anywhere between the feeding line from a single centralized location.
OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to developing an automatic
control system to start/stop all charging section conveyors in desired sequence to
feed raw materials to any blast furnace automatically with a push of a button in
dispatcher room.
A further object of the present invention is directed to developing an automatic
control system to start conveyors in sequence to feed raw material to blast furnace
hoppers in order to reduce the delay in conventional manual start up of charging
section.
A still further object of the present invention is directed to developing an automatic
control system to start conveyors to feed raw material to blast furnace wherein
series of conveyors in a section can be started automatically if the healthy conditions
for start are met.
A still further object of the present invention is directed to developing an automatic
system to start conveyors to feed raw material to blast furnace is adapted to be
started from a single location and by a single push of a button thus reducing manual
delays.
A still further object of the present invention is directed to developing an automatic
system to start conveyors to feed raw material to blast furnace wherein the system
is based on PLC and position sensors such that the position sensor read the start
position of the feeding point and start & stop signal are generated by the PLC based
on the status of the position sensor.
A still further object of the present invention is directed to developing an automatic
system to start conveyors to feed raw material to blast furnace wherein start and
stop of a chain of conveyors can be controlled from anywhere between the feeding
line from a single centralized location.
A still further object of the present invention is directed to developing an automatic
system to start conveyors to feed raw material to blast furnace wherein PLC system
is of rugged modular construction to suit hazardous environment of a Steel Plant
where electromagnetic noise, high temperature or mechanical shock / vibration, dust
etc. are prevalent.
A still further object of the present invention is directed to developing an automatic
system to start conveyors to feed raw material to blast furnace wherein the main
PLC and all the remote I/o Panels are networked for fast data exchange and
information sharing.
A still further object of the present invention is directed to developing an automatic
system to start conveyors to feed raw material to blast furnace wherein all hardware
components are integrated as a system and interfaced with the existing control
electrics to develop desired auto control system for raw material charging conveyors.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is thus directed to a system for
automatized start and stop of a chain of conveyors from a centralized location
comprising:
series of conveyors;
position sensor means to sense the start position of the feeding point of said
conveyors; and
a PLC based unit adapted to generate the start and stop signal based on the status
of the said position sensor.
A further aspect of the present invention is directed to a system for automatized
start and stop of a chain of conveyors from a centralized location for a series of
conveyors to feed raw material to bunkers of different blast furnaces comprising an
auto control system adapted such that that the series of conveyors in a section can
be started automatically if the healthy conditions for start are sensed, inductive
position sensors in trolleys of the conveyor adapted to sense the start position,
section start and stop logic incorporated alongwith with electric and safety interlocks
such that all charging section can be started automatically with a push of a button in
dispatcher unit.
A still further aspect of the present invention is directed to a system for automatized
start and stop of a chain of conveyors from a centralized location wherein to sense
the startup position of each reversible conveyors position sensors are installed, the
conveyors can either feed raw material to one of their own eight bunkers or can send
raw materials down stream to next blast furnace, with built in logic such that for
sending materials down stream the reversible conveyor is maintained in the first
position called the zero position and unless the reversible conveyors are not in zero
possible the downstream conveyors cannot start, the position sensors adapted to
sense this zero position of the conveyors and the control software accordingly
adapted to generate the start/stop command for individual conveyors for the entire
section to start/stop automatically.
A still further aspect of the present invention is directed to a system for automatized
start and stop of a chain of conveyors from a centralized location wherein the PLC
system is of rugged modular construction adapted to be suitable for failsafe
operation in arduous environment of a steel plant .
According to yet another aspect of the present invention is directed to a system for
automatized start and stop of a chain of conveyors from a centralized location
wherein the said conveyor status is obtained in remote I/o stations where the inputs
of the conveyor status are terminated, remote I/o panel houses the remote input
card with network interfaces.
A still further aspect of the present invention is directed to a system for automatized
start and stop of a chain of conveyors from a centralized location wherein main PLC
and all remote I/o Panels are networked for fast data exchange and information
sharing which are integrated as a system and interfaced with the existing control
electrics to develop an auto control system for raw material charging conveyors.
The objects and advantages of the present invention are described in greater details
with reference to the following non limiting accompanying drawing.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1: is the schematic illustration of the auto operation scheme for the charging
conveyors showing a system considering feeding of raw material in bunkers of blast
furnace number 2.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING FIGURES
The present invention relates to developing an automatic control system for
start/stop operation of the charging conveyors for feeding raw material to the Blast
furnaces in steel plant, avoiding any manual intervention and consequent delay.
An automatic control system is developed to start and stop a chain of conveyors
from anywhere between the feeding line from a single centralized location. The
system is based on PLC and position sensors. The position sensor read the start
position of the feeding point and start & stop signal are generated by the PLC based
on the status of the position sensor.
Reference is invited to the accompanying Figure 1 that schematically illustrates the
auto operation scheme for the charging conveyors showing a system considering
feeding of raw material in bunkers of blast furnace number 2. It is clearly apparent
that each charging section comprises of series of conveyors to feed raw material to
bunkers of different blast furnaces and to feed material to bunker of a particular
blast furnace, a series of sequential start up operation for each conveyor is carried
out. When there are five feeding points, all conveyors from the feeding point till the
end are to be started. For example, if the feeding point is five then conveyors 4, 3, 2
& 1 are to started in that sequence. Now for any feeding point the system starts all
the conveyors in the entire line.
According to the present invention a system is developed to reduce the start/stop
time for the entire line and a charging section can be started from a single location
and by a single push of a button thus reducing manual delays. An auto control
system has been implemented so that the series of conveyors in a section can be
started automatically if the healthy conditions for start are met. Inductive position
sensors have been introduced in trolleys of the conveyor to sense the start position.
Section start and stop logic have been developed and incorporated with the existing
electric and safety interlocks so that all charging section can be started automatically
with a push of a button in dispatcher room. This arrangement substantially reduces
the delay involved in conventional manual start up of charging section.
To sense the startup position of each reversible conveyor, position sensors have
been installed. The conveyors can either feed raw material to one of their own eight
bunkers as shown in figure 1, or can send raw materials down stream to next blast
furnace. For sending materials down stream the reversible conveyor should be in the
first position called the zero position. Unless the reversible conveyors are not in zero
position, the downstream conveyors cannot start. This logic has been built into the
present control system. The position sensors sense this zero position of the
conveyors and a control software accordingly generates the start/stop command for
individual conveyors for the entire section to start/stop automatically.
The details of the position sensors used in the system are as follows:
Type : Inductive Proximity
Sensing Distance : 15 mm
Input Voltage : 24 V DC
Outputs : NO / NC contacts
The position sensors read the start position of the feeding point and start & stop
signals are generated by the PLC based on the status of the position sensor.
The PLC system is of rugged modular construction which is designed and
manufactured so as to be suitable for failsafe operation in adverse working
environment of a Steel Plant and where electromagnetic noise, high temperature or
mechanical shock/vibration, dust are prevalent. Thus, high degree of reliability is
built-in by providing carefully selected and rigorously checked components.
Details of PLC System used in the auto control system for raw material charging
conveyor start/stop operation in blast furnaces are as follows:
-Scan time: 1.0ms / K instruction of PLC program.
-Digital I/O handling capacity: 1024 Analog I/O handling capacity: 128
-EEPROM / Flash EPROM battery back up and auto transfer on RAM getting
corrupted.
-CPU Card
-PLC Rack : 12 slot
-PLC power Supply
-Digital Input card 16 Channel, 24 V DC
-Digital output Card 32 channel, 24 V DC
-Ethernet Card
-128 K Flash EEPROM,
There are seven numbers of remote I/o stations where the inputs of the conveyor
status are terminated. The remote I/o panel houses the remote input card with
network interfaces as detailed below:
-Proprietary network interface module
-Power connector Terminal
-24 V DC Power distribution module
-16 Channel 24 V DC Digital input
-4 Channel 24 V DC Output module
-440 / 220 V AC.5 KVA Isolation transformer
The main PLC and all the seven remote I/o Panels are networked for fast data
exchange and information sharing. The following networking hardware have been
used and implemented.
-Line terminator at each end of segment.
-T connections junction box
-network cable
-Repeater
All the above components have been integrated as a system and have been
interfaced with the control electrics to develop an auto control system for raw
material charging conveyors.
It is thus possible by way of the present invention to providing an auto control
system for implementing in blast furnace charging section so that the series of
conveyors in a section can be started automatically if the healthy conditions for start
are met, with a push of a button in dispatcher room. This system avoids human
intervention and substantially reduces the starting time for the charging conveyors.
The system components are rugged and durable in construction to withstand the
adverse working environment at the steel plants to ensure safe and reliable
operation.
We Claim:
1. A system for automatized start and stop of a chain of conveyors from a
centralized location comprising:
series of conveyors;
position sensor means to sense the start position of the feeding point of said
conveyors; and
a PLC based unit adapted to generate the start and stop signal based on the
status of the said position sensor.
2. A system for automatized start and stop of a chain of conveyors from a centralized
location as claimed in claim 1 for a series of conveyors to feed raw material to
bunkers of different blast furnaces comprising an auto control system adapted such
that that the series of conveyors in a section can be started automatically if the
healthy conditions for start are sensed, inductive position sensors in trolleys of the
conveyor adapted to sense the start position, section start and stop logic
incorporated alongwith with electric and safety interlocks such that all charging
section can be started automatically with a push of a button in dispatcher unit.
3. A system for automatized start and stop of a chain of conveyors from a centralized
location as claimed in claim 2 wherein to sense the startup position of each
reversible conveyors position sensors are installed, the conveyors can either feed
raw material to one of their own eight bunkers or can send raw materials down
stream to next blast furnace, with built in logic such that for sending materials down
stream the reversible conveyor is maintained in the first position called the zero
position and unless the reversible conveyors are not in zero possible the downstream
conveyors cannot start, the position sensors adapted to sense this zero position of
the conveyors and the control software accordingly adapted to generate the
start/stop command for individual conveyors for the entire section to start/stop
automatically.
4. A system for automatized start and stop of a chain of conveyors from a centralized
location as claimed in anyone of claims 1 to 3 wherein the PLC system is of rugged
modular construction adapted to be suitable for failsafe operation in arduous
environment of a steel plant .
5. A system for automatized start and stop of a chain of conveyors from a centralized
location as claimed in anyone of claims 1 to 4 wherein the said conveyor status is
obtained in remote I/o stations where the inputs of the conveyor status are
terminated, remote i/o panel houses the remote input card with network interfaces.
6. A system for automatized start and stop of a chain of conveyors from a centralized
location as claimed in anyone of claims 1 to 5 wherein main PLC and all remote I/o
Panels are networked for fast data exchange and information sharing which are
integrated as a system and interfaced with the existing control electrics to develop
an auto control system for raw material charging conveyors.
7. A system for automatized start and stop of a chain of conveyors from a centralized
location substantially as hereindescribed and illustrated with reference to the
accompanying figures.

An automatic control system for start/stop operation of raw material charging
conveyors in blast furnace is disclosed. The system involves a PLC and position
sensors based control to reduce the delay due to manual start up of charging
section, which is implemented in an integrated manner so that the series of
conveyors in a section can be started automatically in sequence if the healthy
conditions for start are met. Importantly, inductive position sensors have been
introduced in trolleys of the conveyor to sense the start position. The position
sensors read the start position of the feeding point and start & stop signals are
generated by the PLC based on the status of the position sensor. Section start and
stop logic have been developed and incorporated with the existing electric and safety
interlocks so that all charging section can be started automatically with a push of a
button in dispatcher room.