FORM 2
THE PATENT ACT 1970
(39 OF 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
1 TITLE OF THE INVENTION :
A SYSTEM FOR CONTROLLING BURNER OPERATION FOR EFFECTIVE GAS MIXING AND BURNER MANAGEMENT FOR IGNITION FURNACE IN SINTER
PLANT.
2 APPLICANT (S)
Name : STEEL AUTHORITY OF INDIA LIMITED.
Nationality : A Govt, of India Enterprise;
Bhilai Steel Plant, Bhilai-490001, State of Chattisgarh,India.
3 PREAMBLE TO THE DESCRIPTION
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to a system for controlling burner operation for effective gas mixing and burner management for ignition furnace for sinter plant. More particularly, the invention is directed to an intelligent system for software enabled selection of control mode of gas mixing to achieve constant Calorific Value (CV) and reliable operation of ignition furnace, selecting gas to air ratio, set points for process parameters as per requirement based on sinter plant operating condition. More particularly, the present invention is directed to providing a system for control of operation of ignition furnace avoiding delay in starting of sinter machine after every small shutdown and also ensure human and equipment safety by minimizing chances of back firing. The system and method of fast, safe and user friendly control of ignition furnace in sinter plant is thus having wide scale prospect of industrial applications.
BACKGROUND ART
It is well known to have conventional systems for gas mixing and control by using human knowledge and experience for proper manual control of operation of ignition furnace in sinter plant.
In the existing gas mixing station and burner management for ignition furnace operation in sinter plant, usually five control valves viz PCV_602A, FCV_602, PCV_601, FCV_603 & FIC_162 or three control valve excluding PCV_602A & PCV_601 are used (as per Figure 5 herein annexed). For Air to gas ratio control, two control valves PIC_167 & FIC_167 are used. Conventionally, for control of Calorific Value in mix gas all these valves are operated in automatic mode and an operator is expected to perform the following operations throughout the process:
1. Manual Changing of controlling mode such as Manual, Auto & Cascade of the controller as and when it is required.
2. Manual Changing of set points of all the controlling parameters as per process requirement.
3. Manual Changing of the ratio of Air to Gas as per process requirement.

4. If gas flow is stopped when sinter machine is shutdown, it needs steam purging before restarting, meaning a loss of production for 10 minutes.
5. Every time machine stops, manual lighting of ignition furnace is required. Here there can be a chance of back firing or gas poisoning in the vicinity if operator is not alert.
It is experienced that it is not at all possible to do all the above stated changes by different operators continuously and correctly, throughout the process. Different operators are having different analyzing power and all cannot think alike and this essentially led to variation in operation. Sintering process in sinter plant wherein minor change in process parameter leads to high sinter return generation either because of un-burnt sinter or because of melting of top layer due of high temperature leading to loss in production. Importantly, it is found that such unwanted variation in process parameter, required shut down of operation and resultantly tend to affect the production. Such interruptions are therefore not desirably as they frequently lead to possible delay in effective maintenance and inefficient use of such gas mixing and burner management system.
There has been thus a continuing need in the art to providing an improved system and method of gas mixing and burner management which would be intelligent and computer controlled, without needing any manual interpretation for control operation and eliminate the associated delay, so that efficiency of sinter machine can be improved by minimizing starting delay.
OBJECTS OF THE INVENTION
It is thus the basic object of the present invention to provide a system for controlling burner operation for effective gas mixing and burner management for ignition furnace of sinter plant, which would avoid the starting delay and improve safety at the shop floor.
Another object of the present invention is to provide a system for controlling burner operation for effective gas mixing and burner management for ignition furnace of

sinter plant which would avoid the problems concerning frequent shut down and complex safety precautions presently required in sinter plant operation.
Yet another object of the present invention is directed to providing a system for controlling burner operation for effective gas mixing and burner management for ignition furnace of sinter plant which would ensure the safety of the instruments and human beings responsible for maintenance of the system without compromising on the efficacy and performance of the system.
A further object of the present invention is directed to providing a system for controlling burner operation for effective gas mixing and burner management for ignition furnace of sinter plant, which would implement software enabled self decision for changing the controlling mode such as Manual, Auto & Cascade, changing of set points for process parameters, or changing of air to gas ratio based on the process condition/requirements which will ensure consistency in the operation, avoid starting delay and improve quality and productivity of sinter in sinter plant.
A further object of the present invention is directed to providing a system for controlling burner operation for effective gas mixing and burner management ignition furnace of sinter plant, favouring reduced return sinter and avoiding melting top layer of sinter bed by controlling ignition intensity inside the ignition furnace.
A still further object of the present invention is directed to providing a system for controlling burner operation for effective gas mixing and burner management for ignition furnace of sinter plant which would minimize the sinter machine down time by avoiding steam purging in case of small duration shut down, by introducing slow burning concept through burner management system.
A still further object of the present invention is directed to providing a system for controlling burner operation for effective gas mixing and burner management for ignition furnace of sinter plant which would minimize the chances of back firing and gas poisoning near ignition furnace area during lighting of ignition furnace by eliminating small duration shut down, by introducing slow burning concept through burner management system.

SUMMARY OF THE INVENTION
The basic aspect of the present invention is directed to a system for controlling burner operation for effective gas mixing and burner management comprising:
means for smooth Ignition startup to set the entire control valve at pre-defined position, and ensure uniform start up in every cycle;
means for monitoring all process conditions and only when all the process conditions are satisfied then only activating opening the shut off valve, ensures safety during start up; and
means adapted such that at every startup, Mix-Gas Flow control valve open to a pre defined position in Manual/Auto mode and control gas flow required for slow burning thereby ensuring stabilization of initial startup condition minimization of startup failure and breakdowns.
A further aspect of the present invention is directed to said system for controlling burner operation for effective gas mixing and burner management for sinter plant as described above further adapted to carry out anyone or more of:
a) Once Sinter Machine starts, all the Set Points achieve their value in a predefined time for smooth startup.
b) Once Mix Gas starts flowing, all the control valves start changing their controlling mode and process set values depending on process conditions.
c) Whenever there is any violation in the safety conditions, shut off valve will close and rest of the control valves wilt go to their predefined position.
d) When machine stops for small duration, furnace goes for slow burning, the same takes care of machine startup delay (minimize delay).
e) For better fuel efficiency Air / Gas ratio is adjusted automatically during slow burning and during norma! ignition.
Yet another aspect of the present invention is directed to said system for controlling burner operation for effective gas mixing and burner management which is adapted such that:

Said start-up with slow burning is effected following the stages defined under accompanying Figure 1;
normal burning conditions are determined based on the stages defined under accompanying Figure 2; and
minor break down is controlled based on the stages defined under accompanying Figure 3.
The present invention and its various objects and advantages are described in greater details with reference to the following accompanying non limiting illustrative drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: is the flow chart showing the stages defined for start-up with slow burning in ignition furnace of sinter plant.
Figure 2: is the flow chart showing stages defined for normal burning conditions in ignition furnace of sinter plant.
Figure 3: is the flow chart showing the stages defining control of minor breakdown condition of ignition furnace in sinter plant.
Figure 4: is the graphical plot of the air flow rate and air to gas ratio corresponding to different controlled operating conditions of the ignition furnace using the system according to the present invention.
Figure 5: is the schematic illustration of the layout diagram showing the arrangements of piping and instruments in the system for Gas Mixing and Booster for Ignition furnace of sinter plant according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
The present invention is directed to providing a system for intelligent burner management system for sinter plant, where too many action is required in short duration during starting and stopping of sinter machine so that the system of the invention enable automatic control of gas mixing to achieve constant Calorific Value (CV) and process control operation of ignition furnace in a safe and reliable manner avoiding back firing and minimizing start up delay of sinter machine after short duration stoppage.
The On-Line Software Model developed for automatic control of Gas Mixing Station and Ignition Furnace of a Sintering Plant according to the present invention, takes care of smooth start and stop as well as normal operation of Ignition Furnace, This model decides and selects the controlling mode e.g. Auto, Cascade or Manual, and selects the required set values for all the control valves as per process requirement, which is otherwise normally done manually by the operator.
Accompanying Figures 1-3 shows the flow charts for the scheme of events that are automatically controlled by the software model of the system for gas mixing and ignition furnace control according to the present invention in a sinter plant under different operating conditions. The system of the present invention operates on a software model which also takes care of all the gas related safety interlocks. The gas flow rate and pressure of coke oven gas, blast furnace gas and the mixed gas is continuously monitored. Provision has also been made in the model for stow burning of gas inside the furnace, if machine stops for small duration to minimize the sinter machine starting delay. Accompanying Figure 1 is the flow chart showing the stages defined for 'start-up with slow burning' in ignition furnace of sinter plant. Figure 2 shows a flow chart highlighting the stages defining the 'normal burning conditions' in ignition furnace of sinter plant. Accompanying Figure 3 is the flow chart showing the stages defining control of 'minor breakdown condition' of ignition furnace in sinter plant.

The system has got total seven-control valve and one shut off valve but most importantly it has to be noted that operator gives only one command that is Ignition Start Command. All other commands for all the control valves is calculated and generated by the software model developed in the PLC.
The software model developed in PLC implements the following activities for control of gas mixing and ignition furnace control:
a) During Ignition startup, it sets the entire control valve at pre-defined position.
b) Once all the process conditions are satisfied then only it allows opening the shut off valve.

c) At every startup, Mix-Gas Flow control valve would open to a pre defined position in Manual/Auto mode and would control gas flow required for slow burning.
d) Once Sinter Machine starts, all the Set Points achieve their value in a predefined time for smooth startup.
e) Once Mix Gas starts flowing, all the control valves start changing their controlling mode and process set values depending on process conditions.
f) Whenever there is any violation in the safety conditions, shut off valve closes and rest of the control valves go to their predefined position.
g) When machine stops for small duration, furnace goes for slow burning. It takes care of machine startup delay (minimize delay).
h) For better fuel efficiency Air / Gas ratio is adjusted automatically during slow burning and during normal ignition.
Accompanying Figure 4 illustrates the graphical plot of the mixed gas flow rate and the air/gas ratio control involving different operating condition of the ignition furnace such as the slow burning at ignition startup, normal burning or burner extinguishing for shut down of small duration of the sinter plant.
It is apparent from the graph of Figure 4 that during slow burning at start up, with flow control auto mode, the flow rate is gradually increased to 600Nm3/hr in auto mode with air ratio of 1.0, when mixed gas flow is further increased up to a flow rate of 1200 Nm3/nr and air ratio of 2.363 to attain normal burning condition. After required time duration, the sintering operation starts and flow rate is further adjusted to 1400 Nm3/nr and air/gas ratio adjusted to 2.953 under normal burning

condition. Once ignition furnace temperature is stabilized, the Temperature control auto mode is selected with flow control in cascade mode with air ratio reduced to 2.363. When all the machine parameters stabilize, Ignition Intensity control auto mode is selected with flow control in cascade mode. Again when the sinter machine stop and flow rate decrement command is given, flow rate and air ratio is reduced in auto mode till the ignition is extinguished.
Accompanying Figure 5 is an illustration of the layout diagram showing the arrangements of piping network and instruments in the system for Gas Mixing and Booster for Ignition furnace of sinter plant according to the present invention. The operation mode and the sequence of operation of the different control valves as well as the shut off valve is as per the details shown in flow chart of accompanying Figure 1-3. The different flow control and pressure control valves as well as the pressure/flow indicator controls are shown in the figure with respective nomenclature for easy identification as per the following details:

Code Abbreviation
PCV601 Coke Oven Gas Pressure Control Valve
PCV602 Blast Furnace Gas Pressure Control Valve
PCV603 Mix Gas Pressure Control Valve
FCV602 Blast Furnace Gas Flow Control Valve
TCV162 Ignition Furnace Temperature Control Valve
FCV167 Combustion air flow control valve
PCV167 Combustion air Pressure control valve
PIC Pressure Indication Control
FIC Flow Indication Control
TIC Temperature Indication Control
IGIC Ignition Intensity Control
It is thus clearly apparent that the software enabled PLC based control system for gas mixing station and ignition furnace operation ensure uniform start up in every cycle and sets all the control valves at pre-defined position. Once all the process conditions are satisfied then only it allows opening the shut off valve, ensuring safety during start up. At every startup, Mix-Gas Flow control valve would open to a pre defined position in Manual/Auto mode and would control gas flow required for slow burning. This ensures stabilization of initial startup condition with minimization of startup failure and breakdowns.

We Claim:
1. A system for controlling burner operation for effective gas mixing and burner
management comprising:
means for smooth Ignition startup to set the entire control valve at pre-defined position, and ensure uniform start up in every cycle;
means for monitoring all process conditions and only when all the process conditions are satisfied then only activating opening the shut off valve, ensures safety during start up; and
means adapted such that at every startup, Mix-Gas Flow control valve open to a pre defined position in Manual/Auto mode and control gas flow required for slow burning thereby ensuring stabilization of initial startup condition minimization of startup failure and breakdowns.
2. A system for controlling burner operation for effective gas mixing and burner
management as claimed in claim 1 for sinter plant further adapted to carry out
anyone or more of;
a) Once Sinter Machine starts, all the Set Points achieve their value in a predefined time for smooth startup.
b) Once Mix Gas starts flowing, all the control valves start changing their controlling mode and process set values depending on process conditions.

c) Whenever there is any violation in the safety conditions, shut off valve will close and rest of the control valves will go to their predefined position.
d) When machine stops for small duration, furnace goes for slow burning, the same takes care of machine startup delay (minimize delay).
e) For better fuel efficiency Air / Gas ratio is adjusted automatically during slow burning and during normal ignition.
3. A system for controlling burner operation for effective gas mixing and burner
management as claimed in anyone of claims 1 or 2 which is adapted such that:
Said start-up with slow burning is effected following the stages defined under accompanying Figure 1;

normal burning conditions are determined based on the stages defined under accompanying Figure 2; and
minor break down is controlled based on the stages defined under accompanying Figure 3.
4. A system for controlling burner operation for effective gas mixing and burner management substantially as hereindescribed and illustrated with reference to the accompanying figures.