Title of Invention	A SYSTEM FOR COAL CARBONIZATION AUTOMATION AND PROCESS CONTROL IN PILOT COKE OVEN
Abstract	A system for coal carbonization automation and process control in pilot coke oven directed to achieve uniform carbonization conditions all through the oven through out the coking process and facilitate monitoring of the pressure and temperature during the carbonization process for effective completion of carbonization. Also the system is adapted to generate continuously monitored data on amperage, voltage and resistance values of all six zones of the oven through out the carbonization period to facilitate failure analysis and taking advance corrective measures. The system is user friendly and is directed to facilitate reliable carbonization by way of better optimization of carbonization blend and process conditions.

Title of Invention

A SYSTEM FOR COAL CARBONIZATION AUTOMATION AND PROCESS CONTROL IN PILOT COKE OVEN

Abstract

A system for coal carbonization automation and process control in pilot coke oven directed to achieve uniform carbonization conditions all through the oven through out the coking process and facilitate monitoring of the pressure and temperature during the carbonization process for effective completion of carbonization. Also the system is adapted to generate continuously monitored data on amperage, voltage and resistance values of all six zones of the oven through out the carbonization period to facilitate failure analysis and taking advance corrective measures. The system is user friendly and is directed to facilitate reliable carbonization by way of better optimization of carbonization blend and process conditions.

Full Text	FIFLD OF THE INVENTION The present invention rebates to pilot coke oven and, in particular, to a system for coal carbonization automation and process control in pilot coke oven directed to achieve uniform carbonization conditions all through the oven through out the coking process and facilitate monitoring of the pressure and temperature during the carbonization process for effective completion of carbonization. Also the system is adapted to generate continuously monitored data on amperage, voltage and resistance values of all six zones of the oven through out the carbonization period to facilitate failure analysis and taking advance corrective measures. The system is user friendly and is directed to facilitate reliable carbonization by way of better optimization of carbonization blend and process conditions. BACKGROUND ART It is well known that pilot coke oven is used worldwide for characterization of coal and coke and evaluation of new coals for coke making. The paste objective of pilot coke oven test for coal carbonization is for blend optimization as well as comparing the quality of coke with respect to blast furnace operation and productivity. Carbonization of coal is a unique process where the heating control placed a pivotal role in coke making. The heat transfer takes place from both side walls through conduction, convection and mainly radiation at high temperatures. The principle of heating is visually based on master-slave PID control. However, in this way the heating at various zones (A1-A2, B1-B2, C1-C2) can not uniform because of door leakage and other parameters resulting in non-uniform heating affecting the coke quality. Carbonization process should take place in absence of air and with a positive pressure in the furnace to Use extent of 10-15 mm. of water column. It is normally difficult to maintain the same pressure inside the furnace during the eighteen hours operation for carbonization process. Carbonization process in any furnace can not be uniform as the coal charge is heated from both the side walls. The heat is transferred from both the walls to the center of the oven and the carbonization is supposed to be completed when the Center coke mass reaches approximately 1000oC. In some countries, however, the center coke temperature is taken between 970° to 990°C as per the prevailing practices. The corresponding coking time depending on the heating rate can vary between 16 to 20 hours. Thus it is impossible to achieve the same 2 coking time for all the coal and coal blend carbonization with the same center coke mass temperature. Practical experience with the 300kg. pilot coke oven reveals that the center cote mass temperature varies more than 50°C under the same coking time. This in turn reflects towards the quality of coke vis-a-vis coke characterization. The comparison of coke produced from the pilot coke oven will not be correct. Therefore, it is necessary to introduce process control of coal carbonization with the help of automation. Carbonization failure analysis of the heating system and other control parameters are also not available worldwide for the testing of coal for carbonization. Because of this, the furnace shut down is frequent resulting in poor coke quality at the end of 16-18 hours of coking time. OBJECTS OF THE INVENTION It is thus the basic object of the present invention to provide coal carbonization automation and process control in pilot coke oven, which would enable achieving uniform carbonization condition all through the oven throughout the colling process. Another object of the present invention is directed to coal carbonization automation and process control in pilot coke oven to achieve uniform temperature through heating control in all the six zones, of two walls of the coke oven. Further object of the present invention is directed to coal carbonization automation and process control in pilot coke oven to achieve uniform positive pressure level of the oven throughout the carbonization period. Another object of the present invention is to achieve coal carbonization automation and process control in pilot coke oven adapted to facilitate continuous monitoring of the wall pressure during carbonization and also to continuously monitor the center coke oven pressure during carbonization. Yet another object of the present invention is directed to coal carbonization automation and process control in pilot coke oven such as to maintain uniform coking time for the same heating rate to achieve completion of carbonization at center coke mass temperature of 1000oC. 3 Yet further object of the present invention in directed to coal carbonization automation and process control in pilot coke oven for continuously monitor the oven pressure throughout the carbonization period and to maintain the pressure level of 10-15mm. of WC (Water Column) Yet another object of the present invention is directed to coal carbonization automation and process control in pilot coke oven for the measurement of the movement of the plastic layer inside the coal mass in the furnace during the carbonization. Yet another object of the present Invention is directed to coal carbonization automation and process control in pilot coke oven for the measure the vertical shrinkage of the coal mass inside the oven during carbonization. Yet further object of the present invention is directed to coal carbonization automation and process control in pilot coke oven to generate historical trend of the carbonization pattern. A further object is also directed to coal carbonization automation and process control in pilot coke oven such as to facilitate the generation of data by logging amperage, voltage and resistance values of all the six zones throughout the carbonization period for continuously monitoring the failure analysis for taking advance corrective measures. SUMMARY OF THE INVENTION Thus, according to the basic aspect of the present invention, there is provided a system for coal carbonization automation and process control in pilot coke oven comprising: uniform temperature heating control means in all the six zones of the two walls of the coke oven ; means for achieving uniform pressure level of the oven throughout the carbonization process; means for continuously monitoring the center coke temperature and pressure during the carbonization; and means For monitoring and achieving uniform carbonization conditions including temperature and pressure throughout the oven and throughout the coking process. 4 According to a preferred aspect of the invention there is provided a system for coal carbonization automation and process control in pilot coke oven comprising: uniform temperature heating control means in all the six zones of the two walls of the coke oven ; means for achieving uniform pressure level of the oven throughout the carbonization process; means for continuously monitoring the center coke temperature and pressure during the carbonization; means for monitoring and achieving uniform carbonization conditions including temperature and pressure throughout the oven throughout the coking process ; and means to generate data by togging amperage, voltage and resistance values of all the six zones throughout the carbonization period for continuously monitoring the failure analysis for advance corrective measures. The above disclosed system of the invention for coal carbonization automation and process control in pilot coke oven comprises means for achieving uniform positive pressure level or the oven throughout the carbonization period ,Also, there is provided means for maintaining uniform coking time for the same heating rate to achieve completion of carbonization at center coke mass temperature of 1000°C,The system includes means for continuously monitoring the oven pressure throughout the carbonization period and to maintain pressure level of 10 to 15 mm of WC (water column). In accordance with another aspect the system further enable measure the movement of plastic layer inside the coal mass in the furnace during carbonization and means to measure the vertical shrinkage of coal mass inside the oven during carbonization. In accordance with a further aspect the system enables generating historical trend of the carbonization pattern. 5 In accordance with a preferred aspect the system comprises balancing of resistance of the heating elements in each zone having 12 elements wherein out of 12 elements in each zone, two are in series in each row, while six of them are connected in parallel from both the ends of the elements; six numbers of current transducers for data logging of the current from six zones separately. According to an embodiment the system can comprise digital inputs for the PLC considering current operated relays for sensing heater current for a group of heating elements, if the current drawn is at a defined level, as the current falls down below the defined level, the corresponding relay gets dosed and the PLC will annunciate a problem with that group. According to another embodiment the system can comprise analog inputs from the current transducers provided for a group of twelve heat elements, if the current drawn by a group of heaters is less than the current drawn by the other two groups by a defined margin , PLC is adapted to annunciate a fault with the concerned group, six numbers of voltage transducers added to said six zones A1-A2, B1-02 and C1-C2 zones to know the zone resistances of the oven during carbonization for uniform heating and the individual heating element adapted for replacement with higher resistance value during oven stand by condition for enhanced life of DS type of silicon carbide elements. For the rate of exhaust gases of the oven to be monitored during carbonization ,the volumetric flow through the orifice of the exhaust pipe adapted to create the positive pressure inside the furnace by natural draft, pressure transmitter in conjunction with a step motor or proportional motor connected to butterfly valve in the exhaust orifice of the pipe is introduced to control the pressure of the furnace accurately and keep the furnace pressure at about 10 mm. water column for the entire carbonization period irrespective of amount of gas flow and the constant natural draft on which the heating process has no control. The process automation for coal carbonization can comprise heating control means preferably 72 numbers D5 type silicon carbide heating element, out of which 36 elements one on each of the wall for heating. 6 In accordance with a preferred aspect the system induces power relays connected to input and output of the transformer tapping, adapted to be triggered based on the temperature profile and programming for the heating control of the coal carbonization through PLC such that Irrespective of any coal blend the desired coke temperature can be achieved in the stipulated coking time of 16-18 hours. A dial up modem installed at one of the PCs adapted to report message / fault to any telephone line in case of system failure already envisaged by the PLC. In accordance with another aspect of the invention there is provided a process automation for coal carbonization comprises carrying out the coal carbonization using the system For coal carbonization automation as discussed above. Preferably, the process automation for coal carbonization comprises initially, for heating the oven for ambient temperature, 90V is applied through transformer tapping for slow heating, in case it is found that after 650°C of the oven temperature 9OV is inadequate , 100V was given for raising the temperature from 650oonwards upto 850°C, coal charge 280 to 300kg. is charged from the top of the oven at 850°C; Raising the voltage to 110V for carbonization of coal charge such that after a spell of time when the moisture and volatile of coke start evolving, coke start forming. Further the above process automation for coal carbonization comprises using power relays connected to input and output of the transformer tapping, which is triggered based on the temperature profile and programming for the heating control of the coat carbonization through PLC whereby irrespective of any coal blend the desired end coke temperature of 1000°C at the oven centre can be achieved in the stipulated cooking time of 16-18 hours, for the uniform carbonization of alt the coal blends under the same heating conditions to produce coke, It is also possible to use a dial up modern installed at one of the PCs to report message / fault to any telephone line in case of system failure already envisaged by the PLC. It would be apparent from the above that the present system would replace earlier system by a PLC processor executing six PID routings for the different heating zones operating on a common reference generated as per desired heating profile. Preferably, the profile is set using MMI (Man Machine Interface) and a comprehensive SCADA (Supervisory Control and Data Acquisition) software consisting both routine and 7 developing packages. Such packages are adapted for use with Windows 95/98, Windows NT and Windows 2000 and has capability to use OLE (Objective Linking and Embedding), ODBC (Open Database Connectivity), DDE (Dynamic Data Exchange), OPC (Object Process Control) and ActiveX technologies for optimum performance and integration with other software systems. The details of the invention, its objects and advantages are explained hereunder in greater details in relation to non limiting exemplary embodiments as per the following accompanying figures: BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES Figure 1 : a schematic diagram of a Pilot Oven; Figure 2 : is an illustration of the temperature distribution across the oven; Figure 3 : PLC system configuration in accordance with the invention. Reference is invited to accompanying Figures 1 to 3 wherein in Figure 1 a Pilot Oven is shown schematically while figure 2 shows the temperature distribution across the oven. In accordance with me system as illustrated in relation to me figure 3, all the heating zones (six) are independently controlled. It is possible to achieve uniform heating control, proceeding from both the wall sides of the oven towards the center. Historical friend, heating and carbonization trend can also be recorded continuously. Pressure transducers attached to the moveable wall and LVDT (Unear Variable Differential Transducer) and pressure transducer from oven top and oven wall is connected to the PLC base system to monitor vertical shrinkage and wall pressure during coat carbonization respectively. All the temperature zones of the oven, center coke mass, wall and auxiliary temperature are monitored simultaneously during carbonization process. The current and voltage for me beating of all six zones of the furnace measured continuously using current and voltage transducers. It is observed that the uniform heating from all the throe zones of both walls require the balancing of resistance of the heating elements in each zone having 12 elements. Out of 12 elements in each zone, two are in series and in each now, while six of them are connected in parallel from both the ends of the elements. This has been developed to ensure minimum heat loss during failure of any elements in a section. Taking the above configuration into consideration, six numbers of current transducers were added for data logging of the current from six zones, separately. At this stage two options have been considered. In Option 1, digital 8 inputs for the PLC considering current operated relays to be used for sensing heater current for a group of heating elements, If the current drawn is at 3 defined level. As the current falls down below the defined level, the corresponding relay gets closed and the PLC will annunciate a problem with that group, In Option 2, analog inputs from the current transducers are provided for 3 group of twelve hearing elements. If the current drawn by a group of heaters is less than the current drawn by the other two groups by a defined margin PLC will annunciate a fault with the concerned group. This arrangement is adapted to reliably sensed a failure even if the current drawn varies over a wide range. Additionally, six numbers of voltage transducers are added to A1-A2, B1- 62 and C1-C2 zones. This is done with a view to know the zone resistances of the oven during carbonization for uniform heating. In case of higher zone resistance more than the specified one as per theoretical calculation, the individual heating element with higher resistance value can be altered during oven stand by condition. In this way, the life of silicon carbide elements can also be enhanced by replacement of elements with the stipulated resistance value. Oven pressure and the center coke mass pressure can be monitored using a special device connected to pressure transmitter. The output of the transmitter is connected to the PLC system for continuous data logging. Under this stage of development of the automation of pilot coke oven, the rate of exhaust gases of the oven is monitored during carbonization which varies with time and type of coal and cost blends used. The volumetric flow through the orifice of the exhaust pipe creates the positive pressure inside the furnace by natural draft Earlier, the pressure of the oven was controlled by varying the diameter of the orifice manually. The orifice is not an appropriate method to control the oven pressure at a constant level. The suitable pressure transmitter in conjunction with a step motor or proportional motor connected to butterfly valve in the exhaust orifice of the pipe is introduced. This has been done with an aim to control the pressure of the furnace accurately and keep the furnace pressure at about 10mm. water column for the entire carbonization period irrespective of amount of gas flow and the constant natural draft on which the carbonization process has no control. The most Important part of the process automation for coal carbonization is heating control which is achieved preferably using 72 numbers DS type silicon carbide heating element, out of which 36 etements on each of the wall for heating. Initially, for heating the oven from ambient temperature, 90V is applied through transformer tapping for slow tosting. It is found that after 650°C of the oven temperature 90V is inadequate and 9 100V was given for raising the temperature from 650°C onwards upto 850°C. Crushed coal / coal blend is charged from the top or the oven at 850°C Carbonization of coal is an endothermic process and therefore requires heat Input and accordingly the voltage is raised to 110V for carbonization. After a spell of time when the moisture and volatile of coke start evolving, coke start forming. The property of coal usually varies from one coal / coal blend to the other with respect to the heat transfer phenomenon. The conductivity and specific heat of the coal, semi coke and coke mass also varies appreciably, which result in different, end coke temperature after fixing coking time. This problem is addressed by fixing power relays connected to input and output of the transformer tapping, which is triggered based on the temperature profile and programming for the heating control of the coal carbonization through PLC. In this way, irrespective of any coal blend end coke temperature say 1000oC can be achieved in the stipulated coking time of 16-18 hours. This ensures the uniform carbonization of all the coal blends under the same heating control to produce coke. In addition, a dial up modem is installed at one of the PCs to report message / fault to any telephone line in case of system failure already envisaged by the PLC It is thus possible by say of above disclosed system to achieve uniform heating control for the entire carbonization period through PLC. Also historical trend for all the carbonization process parameters can be obtained. Uniform pressure during carbonization, center coke mass pressure monitoring, uniform carbonization trend for better comparison of coke for blast furnace, fault finding in-built system, optimization of cold blend for carbonization, reliable comparison of coke qualities obtained from different blends carbonized under same condition are made possible by the present invention. 10 WE CLAIM: 1. A system for coal carbonization automation and process control in pilot coke oven comprising: uniform temperature heating control means in all the six zones of the two walls of the coke oven ; means for achieving uniform pressure level of the overt throughout the carbonization process; means for continuously monitoring the center coke temperature and pressure during the carbonization; and means for monitoring and achieving uniform carbonization conditions including end coke temperature and pressure throughout the oven and throughout the cooking process . 2. A system for coal carbonization automation and process control in pilot coke oven comprising: uniform temperature heating control means in all the six zones of the two walls of the coke oven ; means for achieving uniform pressure level of the oven throughout the carbonization process; means for continuously monitoring the center coke temperature and pressure during the carbonization; means for monitoring and achieving uniform carbonization conditions including end coke temperature and pressure throughout the oven throughout the cooking process ;and means to generate data by logging amperage, voltage and resistance values of all the six zones throughout the carbonization period for continuously monitoring the failure analysis for advance corrective measures. 11 3. A system for coal carbonization automation and process control in pilot coke oven as claimed in anyone of claims 1 or 2 comprising means few achieving uniform positive pressure level of the oven throughout the carbonization period. 4. A system for coal carbonization automation and process control in pilot coke oven as claimed in anyone of claims 1 to 3 comprising means for maintaining uniform cooking time for the same heating rate to achieve completion of carbonization at center coke mass temperature of 1000°C. 5. A system for coal carbonization automation and process control in pilot coke oven as claimed in anyone of claims 1 to 4 comprising means for continuously monitoring the oven pressure throughout the carbonization period and to maintain pressure level of 10 to 15 mm of WC (water column). 6. A system for coal carbonization automation and process control in pilot coke oven as claimed in anyone of claims 1 to 5 comprising means to measure the movement of plastic layer inside the coal mass in the furnace during carbonization. 7. A system for coal carbonization automation and process control in pilot coke oven as claimed in anyone of claims 1 to 6 comprising means to measure the vertical shrinkage of coal mass, inside the oven during carbonization. 8. A system for coal carbonization automation and process control in pilot coke oven as claimed in anyone of claims 1 to 7 comprising generating historical trend of the carbonization pattern. 9. A system for coal carbonization automation and process control in pilot coke oven as claimed in anyone of claims 1 to 3 comprising six PID routines for the different heating zones operatic on a common reference as per desired heating profile set involving a MMI (Man Machine Interface) and a comprehensive SCADA (Supervisory Control and Data Acquisition) software. 10. A system for coal carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 to 9 wherein all the heating zones are adapted to be independently controlled with achieving uniform heating control proceeding from both the wall sides of the oven towards the center. 12 11. A system for coal carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 to 10 comprising pressure transducers attached to be moveable walls and LVDT (linear variable differential transducer) from oven top connected to the PLC base system to monitor wall pressure and vertical shrinkage during coal carbonization respectively 12. A system for coal carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 toll wherein all the temperature zones of the oven, center coke mass, wall and auxiliary temperature are adapted to be monitored simultaneously during carbonization process. 13. A system for coal carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 to 12 comprising current and voltage transducer for continuous measurement of current and voltage. 14. A system for coal carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 to 13 comprising current and voltage transducers adapted to measure continuously the current and voltage for the heating of all six zones of the furnace. 15. A system for coal carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 to 14 comprising balancing of resistance of the heating elements in each zone having 12 elements wherein our of 12 elements in each zone, two are in series and in each row, while six of them are connected in parallel from both the ends of the elements; six numbers of current transducers for data logging of the current from six zones separately. 16. A system for coal carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 to 15 comprising digital inputs for the PLC considering current operated relays for sensing heater current for a group of heating elements, if the current drawn is at a defined levels the current falls down below the defined level, the corresponding relay gets closed and the PLC will annunciate a problem with that group. 13 17. A system for coal carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 to 15 comprising analog inputs from the current transducers provided for a group of four heat elements, if the current drawn by a group of heaters is less than the current drawn by the other two groups by a defined margin , PLC is adapted to annunciate a fault with the concerned group. six numbers of voltage transducers added to said six zones A1-A2,B1-B2 and C1-C2 zones to know the zone resistances of the oven during carbonization for uniform heating and the individual heating dement adapted for replacement with higher resistance value during oven stand by condition for enhanced life of silicon carbide elements. 18. A system for coal carbonization automation and process control in pilot coke overt as claimed in any one of claims 1 to 17 wherein the rate of exhaust gases of the oven is monitored during carbonization, the volumetric flow through the orifice of the exhaust pipe adapted to create the positive pressure inside the furnace by natural draft. , pressure transmitter In conjunction with a step motor of proportional motor connected to butterfly wall in the exhaust orifice of the pipe is introduced to control the pressure of the furnace accurately and keep the furnace pressure at about 10mm. water column for the entire carbonization period irrespective of amount of gas flow and the constant natural draft on which the process has no control. 19. A system for coal carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 to 18 wherein the process automation for coal carbonization comprises heating control means preferably 72 numbers DS type silicon carbide heating element, out of which 36 elements on each of the wall for heating. 20. A system for coat carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 to 19 comprising providing power relays connected to input and output of the transformer tapping, adapted to be triggered based on the temperature profile and programming for the beating control of the coal carbonization through PLC such that irrespective of any coal blend the desired coke temperature can be achieved in the stipulated coking time of 16-18 hours. 21. A system for coal carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 to 20 comprising a dial up modem installed at one of the PCs adapted to report message / fault to any telephone line in case of system failure already envisaged by the PLC 14 21.A process automation for coal carbonization comprises carrying out the coal carbonization using the system for coal carbonization automation and process control in pilot coke oven as claimed in any one of claims 1 to 21. 22. A process automation for coal carbonization as claimed in claim 21 comprising initially, for heating the oven for ambient temperature, 90V is applied through transformer tapping for slow heating, in case it is found that after 650oC of the oven temperature 90V is inadequate , 100V was given for raising the temperature from 650°C onwards upto 850OC, crushed coat / coal blend is charged from the top of the oven at 850°C raising the voltage to 110V for carbonization; such that after a spell of time when the moisture and volatile of coke start evolving, coke start forming. 23. A process automation for coal carbonization as claimed in anyone of claim 20 to 22 comprising using power relays connected to input and output of the transformer tapping, which is triggered based on the temperature profile and programming for the heating control or the coal carbonization through PLC whereby irrespective of any coal blend the desired coke temperature can be achieved in the stipulated coking time of 16- 18 hours. For the uniform carbonization of all the coal blends under the same heating control to produce coke. 24. A process automation for coal carbonization as claimed in anyone of claim 20 to 23 comprising using a dial up modem installed at one of the PCs to report message / fault to any telephone, line to case of system failure already envisaged by the PLC. 15 25. A system for coal carbonization automation and process control in pilot coke oven and a method of using the same for coal carbonization substantially as herein described and illustrated with reference to the accompanying figures. A system for coal carbonization automation and process control in pilot coke oven directed to achieve uniform carbonization conditions all through the oven through out the coking process and facilitate monitoring of the pressure and temperature during the carbonization process for effective completion of carbonization. Also the system is adapted to generate continuously monitored data on amperage, voltage and resistance values of all six zones of the oven through out the carbonization period to facilitate failure analysis and taking advance corrective measures. The system is user friendly and is directed to facilitate reliable carbonization by way of better optimization of carbonization blend and process conditions.

Full Text

FIFLD OF THE INVENTION
The present invention rebates to pilot coke oven and, in particular, to a system for coal
carbonization automation and process control in pilot coke oven directed to achieve
uniform carbonization conditions all through the oven through out the coking process
and facilitate monitoring of the pressure and temperature during the carbonization
process for effective completion of carbonization. Also the system is adapted to generate
continuously monitored data on amperage, voltage and resistance values of all six zones
of the oven through out the carbonization period to facilitate failure analysis and taking
advance corrective measures. The system is user friendly and is directed to facilitate
reliable carbonization by way of better optimization of carbonization blend and process
conditions.
BACKGROUND ART
It is well known that pilot coke oven is used worldwide for characterization of coal and
coke and evaluation of new coals for coke making. The paste objective of pilot coke oven
test for coal carbonization is for blend optimization as well as comparing the quality of
coke with respect to blast furnace operation and productivity.
Carbonization of coal is a unique process where the heating control placed a pivotal role
in coke making. The heat transfer takes place from both side walls through conduction,
convection and mainly radiation at high temperatures. The principle of heating is visually
based on master-slave PID control. However, in this way the heating at various zones
(A1-A2, B1-B2, C1-C2) can not uniform because of door leakage and other parameters
resulting in non-uniform heating affecting the coke quality.
Carbonization process should take place in absence of air and with a positive pressure in
the furnace to Use extent of 10-15 mm. of water column. It is normally difficult to
maintain the same pressure inside the furnace during the eighteen hours operation for
carbonization process. Carbonization process in any furnace can not be uniform as the
coal charge is heated from both the side walls. The heat is transferred from both the
walls to the center of the oven and the carbonization is supposed to be completed when
the Center coke mass reaches approximately 1000oC.
In some countries, however, the center coke temperature is taken between 970° to
990°C as per the prevailing practices. The corresponding coking time depending on the
heating rate can vary between 16 to 20 hours. Thus it is impossible to achieve the same
2

coking time for all the coal and coal blend carbonization with the same center coke mass
temperature. Practical experience with the 300kg. pilot coke oven reveals that the
center cote mass temperature varies more than 50°C under the same coking time. This
in turn reflects towards the quality of coke vis-a-vis coke characterization. The
comparison of coke produced from the pilot coke oven will not be correct. Therefore, it
is necessary to introduce process control of coal carbonization with the help of
automation.
Carbonization failure analysis of the heating system and other control parameters are
also not available worldwide for the testing of coal for carbonization. Because of this, the
furnace shut down is frequent resulting in poor coke quality at the end of 16-18 hours of
coking time.
OBJECTS OF THE INVENTION
It is thus the basic object of the present invention to provide coal carbonization
automation and process control in pilot coke oven, which would enable achieving uniform
carbonization condition all through the oven throughout the colling process.
Another object of the present invention is directed to coal carbonization automation and
process control in pilot coke oven to achieve uniform temperature through heating
control in all the six zones, of two walls of the coke oven.
Further object of the present invention is directed to coal carbonization automation and
process control in pilot coke oven to achieve uniform positive pressure level of the oven
throughout the carbonization period.
Another object of the present invention is to achieve coal carbonization automation and
process control in pilot coke oven adapted to facilitate continuous monitoring of the wall
pressure during carbonization and also to continuously monitor the center coke oven
pressure during carbonization.
Yet another object of the present invention is directed to coal carbonization automation
and process control in pilot coke oven such as to maintain uniform coking time for the
same heating rate to achieve completion of carbonization at center coke mass
temperature of 1000oC.
3

Yet further object of the present invention in directed to coal carbonization automation
and process control in pilot coke oven for continuously monitor the oven pressure
throughout the carbonization period and to maintain the pressure level of 10-15mm. of
WC (Water Column)
Yet another object of the present invention is directed to coal carbonization automation
and process control in pilot coke oven for the measurement of the movement of the
plastic layer inside the coal mass in the furnace during the carbonization.
Yet another object of the present Invention is directed to coal carbonization automation
and process control in pilot coke oven for the measure the vertical shrinkage of the coal
mass inside the oven during carbonization.
Yet further object of the present invention is directed to coal carbonization automation
and process control in pilot coke oven to generate historical trend of the carbonization
pattern.
A further object is also directed to coal carbonization automation and process control in
pilot coke oven such as to facilitate the generation of data by logging amperage, voltage
and resistance values of all the six zones throughout the carbonization period for
continuously monitoring the failure analysis for taking advance corrective measures.
SUMMARY OF THE INVENTION
Thus, according to the basic aspect of the present invention, there is provided a system
for coal carbonization automation and process control in pilot coke oven comprising:
uniform temperature heating control means in all the six zones of the two walls of the
coke oven ;
means for achieving uniform pressure level of the oven throughout the carbonization
process;
means for continuously monitoring the center coke temperature and pressure during the
carbonization; and
means For monitoring and achieving uniform carbonization conditions including
temperature and pressure throughout the oven and throughout the coking process.
4

According to a preferred aspect of the invention there is provided a system for coal
carbonization automation and process control in pilot coke oven comprising:
uniform temperature heating control means in all the six zones of the two walls of the
coke oven ;
means for achieving uniform pressure level of the oven throughout the carbonization
process;
means for continuously monitoring the center coke temperature and pressure during the
carbonization;
means for monitoring and achieving uniform carbonization conditions including
temperature and pressure throughout the oven throughout the coking process ; and
means to generate data by togging amperage, voltage and resistance values of all the
six zones throughout the carbonization period for continuously monitoring the failure
analysis for advance corrective measures.
The above disclosed system of the invention for coal carbonization automation and
process control in pilot coke oven comprises means for achieving uniform positive
pressure level or the oven throughout the carbonization period ,Also, there is provided
means for maintaining uniform coking time for the same heating rate to achieve
completion of carbonization at center coke mass temperature of 1000°C,The system
includes means for continuously monitoring the oven pressure throughout the
carbonization period and to maintain pressure level of 10 to 15 mm of WC (water
column).
In accordance with another aspect the system further enable measure the movement of
plastic layer inside the coal mass in the furnace during carbonization and means to
measure the vertical shrinkage of coal mass inside the oven during carbonization.
In accordance with a further aspect the system enables generating historical trend of
the carbonization pattern.
5

In accordance with a preferred aspect the system comprises
balancing of resistance of the heating elements in each zone having 12 elements wherein
out of 12 elements in each zone, two are in series in each row, while six of them are
connected in parallel from both the ends of the elements;
six numbers of current transducers for data logging of the current from six zones
separately.
According to an embodiment the system can comprise
digital inputs for the PLC considering current operated relays for sensing heater current
for a group of heating elements, if the current drawn is at a defined level, as the current
falls down below the defined level, the corresponding relay gets dosed and the PLC will
annunciate a problem with that group.
According to another embodiment the system can comprise analog inputs from the
current transducers provided for a group of twelve heat elements, if the current drawn
by a group of heaters is less than the current drawn by the other two groups by a
defined margin , PLC is adapted to annunciate a fault with the concerned group,
six numbers of voltage transducers added to said six zones A1-A2, B1-02 and C1-C2
zones to know the zone resistances of the oven during carbonization for uniform heating
and the individual heating element adapted for replacement with higher resistance value
during oven stand by condition for enhanced life of DS type of silicon carbide elements.
For the rate of exhaust gases of the oven to be monitored during carbonization ,the
volumetric flow through the orifice of the exhaust pipe adapted to create the positive
pressure inside the furnace by natural draft, pressure transmitter in conjunction with a
step motor or proportional motor connected to butterfly valve in the exhaust orifice of
the pipe is introduced to control the pressure of the furnace accurately and keep the
furnace pressure at about 10 mm. water column for the entire carbonization period
irrespective of amount of gas flow and the constant natural draft on which the heating
process has no control.
The process automation for coal carbonization can comprise heating control means
preferably 72 numbers D5 type silicon carbide heating element, out of which 36
elements one on each of the wall for heating.
6

In accordance with a preferred aspect the system induces power relays connected to
input and output of the transformer tapping, adapted to be triggered based on the
temperature profile and programming for the heating control of the coal carbonization
through PLC such that Irrespective of any coal blend the desired coke temperature can
be achieved in the stipulated coking time of 16-18 hours.
A dial up modem installed at one of the PCs adapted to report message / fault to any
telephone line in case of system failure already envisaged by the PLC.
In accordance with another aspect of the invention there is provided a process
automation for coal carbonization comprises carrying out the coal carbonization using the
system For coal carbonization automation as discussed above.
Preferably, the process automation for coal carbonization comprises initially, for heating
the oven for ambient temperature, 90V is applied through transformer tapping for slow
heating, in case it is found that after 650°C of the oven temperature 9OV is inadequate ,
100V was given for raising the temperature from 650oonwards upto 850°C, coal charge
280 to 300kg. is charged from the top of the oven at 850°C;
Raising the voltage to 110V for carbonization of coal charge such that after a spell of
time when the moisture and volatile of coke start evolving, coke start forming.
Further the above process automation for coal carbonization comprises using power
relays connected to input and output of the transformer tapping, which is triggered
based on the temperature profile and programming for the heating control of the coat
carbonization through PLC whereby irrespective of any coal blend the desired end coke
temperature of 1000°C at the oven centre can be achieved in the stipulated cooking time
of 16-18 hours, for the uniform carbonization of alt the coal blends under the same
heating conditions to produce coke, It is also possible to use a dial up modern installed
at one of the PCs to report message / fault to any telephone line in case of system
failure already envisaged by the PLC.
It would be apparent from the above that the present system would replace earlier
system by a PLC processor executing six PID routings for the different heating zones
operating on a common reference generated as per desired heating profile. Preferably,
the profile is set using MMI (Man Machine Interface) and a comprehensive SCADA
(Supervisory Control and Data Acquisition) software consisting both routine and
7

developing packages. Such packages are adapted for use with Windows 95/98, Windows
NT and Windows 2000 and has capability to use OLE (Objective Linking and Embedding),
ODBC (Open Database Connectivity), DDE (Dynamic Data Exchange), OPC (Object
Process Control) and ActiveX technologies for optimum performance and integration with
other software systems.
The details of the invention, its objects and advantages are explained hereunder in
greater details in relation to non limiting exemplary embodiments as per the following
accompanying figures:
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1 : a schematic diagram of a Pilot Oven;
Figure 2 : is an illustration of the temperature distribution across the oven;
Figure 3 : PLC system configuration in accordance with the invention.
Reference is invited to accompanying Figures 1 to 3 wherein in Figure 1 a Pilot Oven is
shown schematically while figure 2 shows the temperature distribution across the oven.
In accordance with me system as illustrated in relation to me figure 3, all the heating
zones (six) are independently controlled. It is possible to achieve uniform heating
control, proceeding from both the wall sides of the oven towards the center. Historical
friend, heating and carbonization trend can also be recorded continuously. Pressure
transducers attached to the moveable wall and LVDT (Unear Variable Differential
Transducer) and pressure transducer from oven top and oven wall is connected to the
PLC base system to monitor vertical shrinkage and wall pressure during coat
carbonization respectively. All the temperature zones of the oven, center coke mass, wall
and auxiliary temperature are monitored simultaneously during carbonization process.
The current and voltage for me beating of all six zones of the furnace measured
continuously using current and voltage transducers. It is observed that the uniform
heating from all the throe zones of both walls require the balancing of resistance of the
heating elements in each zone having 12 elements. Out of 12 elements in each zone,
two are in series and in each now, while six of them are connected in parallel from both
the ends of the elements. This has been developed to ensure minimum heat loss during
failure of any elements in a section. Taking the above configuration into consideration,
six numbers of current transducers were added for data logging of the current from six
zones, separately. At this stage two options have been considered. In Option 1, digital
8

inputs for the PLC considering current operated relays to be used for sensing heater
current for a group of heating elements, If the current drawn is at 3 defined level.
As the current falls down below the defined level, the corresponding relay gets closed
and the PLC will annunciate a problem with that group, In Option 2, analog inputs from
the current transducers are provided for 3 group of twelve hearing elements. If the
current drawn by a group of heaters is less than the current drawn by the other two
groups by a defined margin PLC will annunciate a fault with the concerned group. This
arrangement is adapted to reliably sensed a failure even if the current drawn varies over
a wide range. Additionally, six numbers of voltage transducers are added to A1-A2, B1-
62 and C1-C2 zones. This is done with a view to know the zone resistances of the oven
during carbonization for uniform heating. In case of higher zone resistance more than
the specified one as per theoretical calculation, the individual heating element with
higher resistance value can be altered during oven stand by condition. In this way, the
life of silicon carbide elements can also be enhanced by replacement of elements with
the stipulated resistance value.
Oven pressure and the center coke mass pressure can be monitored using a special
device connected to pressure transmitter. The output of the transmitter is connected to
the PLC system for continuous data logging. Under this stage of development of the
automation of pilot coke oven, the rate of exhaust gases of the oven is monitored during
carbonization which varies with time and type of coal and cost blends used. The
volumetric flow through the orifice of the exhaust pipe creates the positive pressure
inside the furnace by natural draft Earlier, the pressure of the oven was controlled by
varying the diameter of the orifice manually. The orifice is not an appropriate method to
control the oven pressure at a constant level. The suitable pressure transmitter in
conjunction with a step motor or proportional motor connected to butterfly valve in the
exhaust orifice of the pipe is introduced. This has been done with an aim to control the
pressure of the furnace accurately and keep the furnace pressure at about 10mm. water
column for the entire carbonization period irrespective of amount of gas flow and the
constant natural draft on which the carbonization process has no control.
The most Important part of the process automation for coal carbonization is heating
control which is achieved preferably using 72 numbers DS type silicon carbide heating
element, out of which 36 etements on each of the wall for heating. Initially, for heating
the oven from ambient temperature, 90V is applied through transformer tapping for slow
tosting. It is found that after 650°C of the oven temperature 90V is inadequate and
9

100V was given for raising the temperature from 650°C onwards upto 850°C. Crushed
coal / coal blend is charged from the top or the oven at 850°C
Carbonization of coal is an endothermic process and therefore requires heat Input and
accordingly the voltage is raised to 110V for carbonization. After a spell of time when the
moisture and volatile of coke start evolving, coke start forming. The property of coal
usually varies from one coal / coal blend to the other with respect to the heat transfer
phenomenon. The conductivity and specific heat of the coal, semi coke and coke mass
also varies appreciably, which result in different, end coke temperature after fixing
coking time. This problem is addressed by fixing power relays connected to input and
output of the transformer tapping, which is triggered based on the temperature profile
and programming for the heating control of the coal carbonization through PLC. In this
way, irrespective of any coal blend end coke temperature say 1000oC can be achieved in
the stipulated coking time of 16-18 hours. This ensures the uniform carbonization of all
the coal blends under the same heating control to produce coke.
In addition, a dial up modem is installed at one of the PCs to report message / fault to
any telephone line in case of system failure already envisaged by the PLC
It is thus possible by say of above disclosed system to achieve uniform heating control
for the entire carbonization period through PLC. Also historical trend for all the
carbonization process parameters can be obtained. Uniform pressure during
carbonization, center coke mass pressure monitoring, uniform carbonization trend for
better comparison of coke for blast furnace, fault finding in-built system, optimization of
cold blend for carbonization, reliable comparison of coke qualities obtained from different
blends carbonized under same condition are made possible by the present invention.
10

WE CLAIM:
1. A system for coal carbonization automation and process control in pilot coke oven
comprising:
uniform temperature heating control means in all the six zones of the two walls of the
coke oven ;
means for achieving uniform pressure level of the overt throughout the carbonization
process;
means for continuously monitoring the center coke temperature and pressure during the
carbonization; and
means for monitoring and achieving uniform carbonization conditions including end coke
temperature and pressure throughout the oven and throughout the cooking process .
2. A system for coal carbonization automation and process control in pilot coke oven
comprising:
uniform temperature heating control means in all the six zones of the two walls of the
coke oven ;
means for achieving uniform pressure level of the oven throughout the carbonization
process;
means for continuously monitoring the center coke temperature and pressure during the
carbonization;
means for monitoring and achieving uniform carbonization conditions including end coke
temperature and pressure throughout the oven throughout the cooking process ;and
means to generate data by logging amperage, voltage and resistance values of all the
six zones throughout the carbonization period for continuously monitoring the failure
analysis for advance corrective measures.
11

3. A system for coal carbonization automation and process control in pilot coke oven as
claimed in anyone of claims 1 or 2 comprising means few achieving uniform positive
pressure level of the oven throughout the carbonization period.
4. A system for coal carbonization automation and process control in pilot coke oven as
claimed in anyone of claims 1 to 3 comprising means for maintaining uniform cooking
time for the same heating rate to achieve completion of carbonization at center coke
mass temperature of 1000°C.
5. A system for coal carbonization automation and process control in pilot coke oven as
claimed in anyone of claims 1 to 4 comprising means for continuously monitoring the
oven pressure throughout the carbonization period and to maintain pressure level of 10
to 15 mm of WC (water column).
6. A system for coal carbonization automation and process control in pilot coke oven as
claimed in anyone of claims 1 to 5 comprising means to measure the movement of
plastic layer inside the coal mass in the furnace during carbonization.
7. A system for coal carbonization automation and process control in pilot coke oven as
claimed in anyone of claims 1 to 6 comprising means to measure the vertical shrinkage
of coal mass, inside the oven during carbonization.
8. A system for coal carbonization automation and process control in pilot coke oven as
claimed in anyone of claims 1 to 7 comprising generating historical trend of the
carbonization pattern.
9. A system for coal carbonization automation and process control in pilot coke oven as
claimed in anyone of claims 1 to 3 comprising six PID routines for the different heating
zones operatic on a common reference as per desired heating profile set involving a
MMI (Man Machine Interface) and a comprehensive SCADA (Supervisory Control and
Data Acquisition) software.
10. A system for coal carbonization automation and process control in pilot coke oven as
claimed in any one of claims 1 to 9 wherein all the heating zones are adapted to be
independently controlled with achieving uniform heating control proceeding from both
the wall sides of the oven towards the center.
12

11. A system for coal carbonization automation and process control in pilot coke oven as
claimed in any one of claims 1 to 10 comprising pressure transducers attached to be
moveable walls and LVDT (linear variable differential transducer) from oven top
connected to the PLC base system to monitor wall pressure and vertical shrinkage during
coal carbonization respectively
12. A system for coal carbonization automation and process control in pilot coke oven as
claimed in any one of claims 1 toll wherein all the temperature zones of the oven,
center coke mass, wall and auxiliary temperature are adapted to be monitored
simultaneously during carbonization process.
13. A system for coal carbonization automation and process control in pilot coke oven as
claimed in any one of claims 1 to 12 comprising current and voltage transducer for
continuous measurement of current and voltage.
14. A system for coal carbonization automation and process control in pilot coke oven as
claimed in any one of claims 1 to 13 comprising current and voltage transducers adapted
to measure continuously the current and voltage for the heating of all six zones of the
furnace.
15. A system for coal carbonization automation and process control in pilot coke oven as
claimed in any one of claims 1 to 14 comprising
balancing of resistance of the heating elements in each zone having 12 elements
wherein our of 12 elements in each zone, two are in series and in each row, while six of
them are connected in parallel from both the ends of the elements;
six numbers of current transducers for data logging of the current from six zones
separately.
16. A system for coal carbonization automation and process control in pilot coke oven as
claimed in any one of claims 1 to 15 comprising
digital inputs for the PLC considering current operated relays for sensing heater current
for a group of heating elements, if the current drawn is at a defined levels the current
falls down below the defined level, the corresponding relay gets closed and the PLC will
annunciate a problem with that group.
13

17. A system for coal carbonization automation and process control in pilot coke oven as
claimed in any one of claims 1 to 15 comprising analog inputs from the current
transducers provided for a group of four heat elements, if the current drawn by a group
of heaters is less than the current drawn by the other two groups by a defined margin ,
PLC is adapted to annunciate a fault with the concerned group.
six numbers of voltage transducers added to said six zones A1-A2,B1-B2 and C1-C2
zones to know the zone resistances of the oven during carbonization for uniform heating
and the individual heating dement adapted for replacement with higher resistance value
during oven stand by condition for enhanced life of silicon carbide elements.
18. A system for coal carbonization automation and process control in pilot coke overt as
claimed in any one of claims 1 to 17 wherein the rate of exhaust gases of the oven is
monitored during carbonization, the volumetric flow through the orifice of the exhaust
pipe adapted to create the positive pressure inside the furnace by natural draft. ,
pressure transmitter In conjunction with a step motor of proportional motor connected to
butterfly wall in the exhaust orifice of the pipe is introduced to control the pressure of
the furnace accurately and keep the furnace pressure at about 10mm. water column for
the entire carbonization period irrespective of amount of gas flow and the constant
natural draft on which the process has no control.
19. A system for coal carbonization automation and process control in pilot coke oven as
claimed in any one of claims 1 to 18 wherein the process automation for coal
carbonization comprises heating control means preferably 72 numbers DS type silicon
carbide heating element, out of which 36 elements on each of the wall for heating.
20. A system for coat carbonization automation and process control in pilot coke oven as
claimed in any one of claims 1 to 19 comprising providing power relays connected to
input and output of the transformer tapping, adapted to be triggered based on the
temperature profile and programming for the beating control of the coal carbonization
through PLC such that irrespective of any coal blend the desired coke temperature can
be achieved in the stipulated coking time of 16-18 hours.
21. A system for coal carbonization automation and process control in pilot coke oven as
claimed in any one of claims 1 to 20 comprising a dial up modem installed at one of the
PCs adapted to report message / fault to any telephone line in case of system failure
already envisaged by the PLC
14

21.A process automation for coal carbonization comprises carrying out the coal
carbonization using the system for coal carbonization automation and process control in
pilot coke oven as claimed in any one of claims 1 to 21.
22. A process automation for coal carbonization as claimed in claim 21 comprising
initially, for heating the oven for ambient temperature, 90V is applied through
transformer tapping for slow heating, in case it is found that after 650oC of the oven
temperature 90V is inadequate , 100V was given for raising the temperature from 650°C
onwards upto 850OC, crushed coat / coal blend is charged from the top of the oven at
850°C
raising the voltage to 110V for carbonization;
such that after a spell of time when the moisture and volatile of coke start evolving, coke
start forming.
23. A process automation for coal carbonization as claimed in anyone of claim 20 to 22
comprising using power relays connected to input and output of the transformer
tapping, which is triggered based on the temperature profile and programming for the
heating control or the coal carbonization through PLC whereby irrespective of any coal
blend the desired coke temperature can be achieved in the stipulated coking time of 16-
18 hours. For the uniform carbonization of all the coal blends under the same heating
control to produce coke.
24. A process automation for coal carbonization as claimed in anyone of claim 20 to 23
comprising using a dial up modem installed at one of the PCs to report message / fault
to any telephone, line to case of system failure already envisaged by the PLC.
15
25. A system for coal carbonization automation and process control in pilot coke oven
and a method of using the same for coal carbonization substantially as herein described
and illustrated with reference to the accompanying figures.

A system for coal carbonization automation and process control in pilot coke oven
directed to achieve uniform carbonization conditions all through the oven through
out the coking process and facilitate monitoring of the pressure and temperature
during the carbonization process for effective completion of carbonization. Also the
system is adapted to generate continuously monitored data on amperage, voltage
and resistance values of all six zones of the oven through out the carbonization
period to facilitate failure analysis and taking advance corrective measures. The
system is user friendly and is directed to facilitate reliable carbonization by way of
better optimization of carbonization blend and process conditions.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=1pOZ2tQjqfLypxRo8lFT3g==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

269041

Indian Patent Application Number

156/KOL/2006

PG Journal Number

40/2015

Publication Date

02-Oct-2015

Grant Date

29-Sep-2015

Date of Filing

21-Feb-2006

Name of Patentee

STEEL AUTHORITY OF INDIA LIMITED

Applicant Address

RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, DORANDA, RANCHI-834002

Inventors:

#	Inventor's Name	Inventor's Address
1	MUKHERJEE TANMOY KUMAR	RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., RANCHI-834002, STATE OF JHARKHAND, INDIA.

PCT International Classification Number

C10B27/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA