Claims:We claim:
1. A method (300) for prevention of clogging in tundish during continuous casting of steel, the method comprising:
receiving (301) data of molten steel ingredients;
receiving (302) data of steel making parameters;
receiving (303) data of casting parameters
processing (304) the received data of the steel ingredients, the steel making parameters, and the casting parameters using logit regression to determine probability prediction index (B); and
determining (305) probability (C) of clogging based on the determined probability prediction index (B).
2. The method as claimed in claim 1, wherein the method further comprising:
displaying (306) the determined probability (C) on a display unit (208).
3. The method as claimed in claim 1, wherein the data of steel ingredients includes amount of aluminium, Sulphur, phosphorus, calcium, iron oxide, manganese oxide in molted steel at various stages of steel making.
4. The method as claimed in claim 1, wherein the received steel making parameters includes primary steel making parameters and secondary steel making parameters.
5. The method as claimed in claim 4, wherein the primary steel making parameters comprises: Hot metal chemical analysis, Basic oxygen furnace(BOF) treatment end chemical analysis, Re-blow oxygen volume, blow end to tapping start duration, tapping additions, BOF slag carryover.
6. The method as claimed in claim 4, wherein the secondary steel making parameters comprises: arcing duration, Bottom argon purging amount, top lance argon purging amount, Flux additives, Ferro-alloy additives, inclusion modification additives, slag chemical analysis, treatment duration, Liquid steel temperature at different treatment phases, change in liquid steel chemical composition during different treatment phases.
7. The method as claimed in claim 1, wherein the received casting parameters comprises: drop in tundish weight while ladle open, tundish weight during connection of heat, carryover slag volume from ladle to tundish, liquid steel temperature in tundish, liquidus temperature of steel.
8. The method as claimed in claim 1, wherein the method further comprises treating the steel with calcium silicide (CaSi) when the determined probability suggests clogging in tundish 103.
9. A clogging probability determining system (200) for prevention of clogging in tundish during continuous casting of steel, the system (200) comprising:
a data processing module (205) coupled with a processor (201) and a memory (203) to:
receive data of steel ingredients, steel making parameters, and casting parameters;
determine probability prediction index (B) ; and
a probability determining module (206) coupled to the processor (201) and the memory (203) to:
determine, based on the probability prediction index (B), probability of clogging.

10. The clogging probability determining system (200) as claimed in claim 9, wherein the system (200) further comprises:
a display unit (208) to display the determined probability of clogging in tundish at the time of heat open.
11. The clogging probability determining system (200) as claimed in claim 9, wherein the data of steel ingredients includes amount of aluminium, Sulphur, phosphorus, calcium, iron oxide, manganese oxide in molted steel at various stages of steel making.
12. The clogging probability determining system (200) as claimed in claim 9, wherein the received steel making parameters includes primary steel making parameters and secondary steel making parameters.
13. The clogging probability determining system (200) as claimed in claim 12, wherein the primary steel making parameters comprises: Hot metal chemical analysis, Basic oxygen furnace(BOF) treatment end chemical analysis, Re-blow oxygen volume, blow end to tapping start duration, tapping additions, BOF slag carryover.
14. The clogging probability determining system (200) as claimed in claim 12, wherein the secondary steel making parameters comprises: arcing duration, Bottom argon purging amount, top lance argon purging amount, Flux additives, Ferro-alloy additives, inclusion modification additives, slag chemical analysis, treatment duration, Liquid steel temperature at different treatment phases, change in liquid steel chemical composition during different treatment phases.
15. The clogging probability determining system (200) as claimed in claim 12, wherein the received casting parameters comprises: drop in tundish weight while ladle open, tundish weight during connection of heat, carryover slag volume from ladle to tundish, liquid steel temperature in tundish, liquidus temperature of steel.
, Description:A METHOD AND A SYSTEM FOR PREVENTION OF CLOGGING IN TUNDISH DURING CONTINIOUS CASTING OF STEEL
FIELD OF INVENTION:
[001] The present subject matter described herein, relates to a method and a system for prevention of clogging in tundish during continuous casting of steel. The present subject matter, in particularly, relates to a method and a system for determining the probability of clogging at the time of heat open to take corrective action timely during continuous casting of steel to avoid sudden stopper drop and casting outage.
BACKGROUND AND PRIOR ART AND PROBLEM IN PRIOR ART:
[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[003] Continuous casting is a process in which liquid steel 102 is solidified in a desired shape. Figure 1 illustrates schematics of casting machine 100. Referring to figure 1, in continuous casting process steel 102 from ladle 101 is poured into a water-cooled copper mould 107 via tundish. As the cast strand descends from the mould 106, its surface is cooled by water spray 107 or water mist, and the thickness of the shell increases progressively. The cast strand is continuously withdrawn from the bottom of the mould 106 as a shell begins to form around the molten metal. The key control parameter of continuous casting is matching the flow of liquid steel 102 into the mould 106 with the withdrawal speed of the cast strand out of the mould 106. This control of flow rates is maintained by tundish 103 which is a refractory lined vessel acting like a buffer between ladle 101 and mould 106 with the sub-entry nozzle (SEN) 105 and stopper 104 mechanism.
[004] Continuous casting of low carbon aluminium killed steel is commonly associated with clogging of tundish 103 nozzle or sub entry nozzle (SEN) 105. During continuous casting process, inclusions from steel accumulate and clog tundish 103 nozzle and outlet ports of SEN 105, which results in reduced metal throughput. The metal throughput is controlled by opening of SEN 105 bore by stopper mechanism of stopper rod 104. In the stopper mechanism, the stopper rod 104 moves up and down to maintain the required casting throughput. If any increase in stopper opening occurs without any change in casting speed and width, it indicates deposition of inclusions in the tundish 103 nozzle and used as indicator for clogging. These clogs if breaks off or get detached from the nozzle and flush out in metal results in poor internal quality of the casted steel. In case, when these clogs do not break while casting process, the casting throughput get reduced and eventually results in caster outage.
[005] Some methods and systems are currently in use to identify clogging and controlling clogging but none of the method or system determine the probability of clogging during heat open. Further, currently available methods and systems does not provide sufficient time to the operator to reduce clogging or to convert solid inclusion of steel into liquid.
[006] Korean Patent publication number KR2004050195A provides a method to detect mould level change and predict clogging using level deviation to improve clogging.
[007] Korean patent publication number KR2004054269A provides detection of SEN vibration based on falling of clogged material and identifying the cast product for scarfing and avoiding defect in further processing of the product.
[008] Indian patent publication number IN201300351I2 describes an on-line continuous method of measuring clogging. It uses liner equation to convert tundish weight to tundish height. It predicts clogging index using stopper position, tundish weight, actual throughput, mould cross-sectional area data from the control system. The predicted clogging index is then used as decision enabler for inert gas flushing to the casting nozzle and decision making of timely change of tube and tundish during casting.
[009] Korean patent publication number KR2011121041A describes a method that determines the height of the stopper and estimate extent of clogging degree of SEN and then estimates time for changing the submerged nozzle.
[0010] Korean patent number KR2014017168A provides clogging prediction using initial height of stopper, discharge rate of molten steel and theory rate of stopper.
[0011] Korean patent publication number KR470654B1 describes a method to quantify degree of clogging using vibration inside SEN and reduce clogging by control of proper amount of inert gas blown into the submerged nozzle and upper nozzle according to the quantified clogging degree value.
[0012] Korean patent publication number KR2004055973A designed SEN to guide the flow to reduce clogging.
[0013] Korean patent publication number KR2003053143A describe a method of reducing clogging by making clean steel and maintaining calcium to aluminium and calcium to sulphur ratio for specific steel chemistry.
[0014] Indian patent publication number IN201001206I2 describes a method of flux addition, de-oxidation practice and its refining in Ladle Furnace (LF) to produce clean LCAK steel. The method ensures low level of oxygen and sulphur in steel and avoid clogging of ladle nozzle and Sub-Entry Nozzle.
[0015] Indian patent publication number IN200900923I2 provides a purging system and method to use it to reduce clogging during casting.
[0016] Korean patent publication number KR2004055325A describes a method of feeding calcium in molten steel, using ladle bottom blowing and flux to reduces amount of inclusions in molten steel and prevents inclusions from adhering to submerged entry nozzle to prevent clogging of the nozzle.
[0017] Korean patent publication number KR2016126516A describes a method to reduce clogging by injecting oxidizing agent in molten steel to suppress the attachment or growth of the calcium sulfide inclusion in tundish immersion nozzle inner wall.
[0018] Korean patent publication number KR2001063509A talks about tundish slide gate mechanism uses to reduce clogging of SEN bore.
[0019] Korean patent publication number KR312128B1 provides method to reduce clogging by action of ca in steel based on oxygen and aluminium content of steel.
[0020] Korean patent publication number KR2001063548A describes a method of reducing blowholes and entrainment of slag due to vortex in tundish by modifying flow from tundish to SEN using eccentric slot nozzle.
[0021] US patent publication number US6074600A provides a method to reduce clogging by channeling of liquid metal flow with modified tundish accessories. Gas bubble and slag entrainment in the steel reduced was also reduced.
[0022] Korean patent publication number KR815446B1 provides a method to reduce clogging by uniformly spraying molten metal through the exhaust port and blocking the reverse current of metal with SEN design modification.
[0023] Technical problem: the method and systems disclosed in above mentioned patents cannot provide probability of clogging before actual clogging occurs. They merely give the extent of clogging once the clogging is started and the operator can only take measure to reduce the clogging which already occur in tundish.
[0024] Technical objective: To address the above issues a method and a system is required to prevent clogging in tundish during continuous casting process. The present invention determines the probability of clogging in tundish during heat open so that timely action can be taken by operator to prevent it.
[0025] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

OBJECTS OF THE INVENTION:
[0026] It is therefore the object of the present subject matter to overcome the aforementioned and other drawbacks in prior method/product/apparatus.
[0027] The principal objective of the present subject matter is to develop a method and system to prevent clogging in tundish during continuous casting of steel.
[0028] Another object of the present subject matter is to develop a method and system to reduce production of downgraded steel due to clogging.
[0029] Another object of the present subject matter is to develop a method and system to increase the efficiency of continuous casting of steel.
[0030] Yet another object of the present subject matter is to maintain the flow of steel from tundish to mould.
[0031] Yet another object of the present subject matter is to provide a method and a system to control the flow of steel from tundish to mould effectively.
[0032] Yet another object of the present subject matter is to provide a method and a system to reduce clogging already occurred in tundish.
[0033] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
SUMMARY OF THE INVENTION:
[0034] One or more drawbacks of conventional method for prevention of clogging, and additional advantages are provided through the method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.
[0035] The present subject matter relates to a method and a system to prevent clogging, by determining the probability of clogging at the time of heat open to take timely action to avoid clogging during continuous casting of steel.
[0036] In an embodiment, the present subject matter discloses a method for prevention of clogging in tundish during continuous casting of steel. The present method comprising: receiving information of molten steel ingredients along with steel making parameters and casting parameters. Further, processing the received data of the steel ingredients, the steel making parameters, and the casting parameters using logit regression to derive an empirical relation between the parameters to determine probability prediction Index and determining the probability of clogging in tundish using the probability prediction index B.
[0037] In another embodiment, the present subject matter discloses a system comprises a processing module coupled with a processor to process the received data of the steel ingredients, the steel making parameters, and the casting parameters using logit regression to derive an empirical relation to obtain probability prediction index and determining probability of clogging based on the probability prediction index. Further, the system is coupled with a memory unit and a display unit to store data and to display the probability of clogging in tundish at the time of heat open.
[0038] In an aspect, the received steel ingredients include amount of aluminium, Sulphur, phosphorus, calcium, iron oxide, manganese oxide in molten steel at various stages of steel making.
[0039] In an aspect, the received steel making parameters includes primary steel making parameters and secondary steel making parameters.
[0040] In an aspect, the primary steel making parameters are Hot metal chemical analysis, Basic oxygen furnace (BOF) treatment end chemical analysis, Re-blow oxygen volume, blow end to tapping start duration, tapping additions, BOF slag carryover.
[0041] In an aspect, the secondary steel making parameters are arcing duration, Bottom argon purging amount, top lance argon purging amount, Flux additives, Ferro-alloy additives, inclusion modification additives, slag chemical analysis, treatment duration, Liquid steel temperature at different treatment phases, change in liquid steel chemical composition during different treatment phases.
[0042] In an aspect, the received casting parameters are drop in tundish weight while ladle open, tundish weight during connection of heat, carryover slag volume from ladle to tundish, liquid steel temperature in tundish, liquidus temperature of steel.
[0043] In an aspect, the received data of the steel ingredients, the steel making parameters, and the casting parameters is processed using logit regression to derive an empirical relation to determine probability prediction index B.
[0044] In an aspect, the determined probability prediction index is used to determine the probability of clogging in tundish.
[0045] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
[0046] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0048] Fig. 1 illustrates schematics of casting machine;
[0049] Fig. 2 illustrates system for determining probability of clogging in tundish during heat open, in accordance with an embodiment of the present subject matter; and
[0050] Fig. 3 illustrates a method for determining probability of clogging in tundish during heat open, in accordance with an embodiment of the present subject matter.
[0051] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0052] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[0053] The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, system, assembly that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
[0054] The present subject matter relates to a method and system to prevent clogging, by determining the probability of clogging at the time of heat open so that a timely action can be taken to avoid clogging during continuous casting of steel. The present method and the present system work in the casting machine 100 as explained in the figure 1. The present method and the present system use the ingredients of steel to know nature and extent of clogging. Accordingly, a suitable remedy for the same can be taken to eliminate or reduce or avoid clogging in the tundish 103. As for aluminum-killed steel and the like, aluminum, which is added as a deoxidizer, the aluminum reacts with oxygen existing in the molten steel to produce non-metallic inclusions, such as alumina. Therefore, in casting the aluminum-killed steel and the like, the non-metallic inclusions, such as the alumina adheres and accumulates onto the surface of the tundish 103 nozzle or sub entry nozzle (SEM) 105, so that the nozzle is narrowed or clogged up in the worst case, which makes steel casting difficult. Furthermore, the non-metallic inclusions, such as the alumina adhered or accumulated onto the surface of the nozzle or SEM 105 peels off or falls down, and is entrapped in the cast steel strand, thus degrading the quality of the cast steel strand. The qualitative and quantitative assessment of ingredients of steel at various stages of steel making are analyzed to determine their role in generation of alumina inclusion either by de-oxidation or re-oxidation process. After analyzing, the ingredient of steel and the process of steel making which are responsible for generation of kind of alumina based inclusion whose solidification temperature are higher than casting temperature and are non-wetting to steel is considered for determining probability of clogging. Amount of aluminium, Sulphur, phosphorus, calcium, iron oxide, manganese oxide, etc., is determined at various stages so that possibility of occurrence of clogging in a particular heat is determined.
[0055] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0056] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0057] Referring to Figure 2 illustrating a system 200 for prevention of clogging in tundish 103 during continuous casting of steel according to an embodiment of present invention. The present clogging probability determining system 200 (hereinafter can be interchangeably referred as system 200) includes a processor(s) 201, an interface(s) 202, and a memory 203. The processor(s) 201 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, logic circuitries, and/or any devices that manipulate data based on operational instructions given or stored in the memory 203. Among other capabilities, the one or more processor(s) are configured to fetch and execute computer-readable instructions and one or more routines stored in the memory. The memory 203 may store one or more computer-readable instructions or routines, which may be fetched and executed to determine probability of clogging over a network service. The memory 203 may include any non-transitory storage device including, for example, volatile memory, such as RAM, or non-volatile memory, such as EPROM, flash memory, and the like.
[0058] The interface(s) 202 may include a variety of interfaces, for example, interfaces for data input and output devices referred to as I/O devices, storage devices, and the like. The interface(s) 202 may facilitate communication of the clogging probability determining system 200 with various devices, such as display unit 208 and casting machine 200. The interface(s) 202 may also provide a communication pathway for one or more components, such as sensors of the clogging probability determining system 200.
[0059] The system 200 includes module(s) 204 and data 207. The module(s) 204 and the data 207 are communicatively coupled with the processor 201 for processing of the instructions. The modules 204 further includes a data processing module 205 and a probability determining module 206 that may be implemented as a combination of hardware and programming (for example, programmable instructions) to implement one or more functionalities. In examples described herein, such combinations of hardware and programming may be implemented in several different ways. For example, the programming for the processing module 205 and the probability determining module 206 may be processor executable instructions stored on a non-transitory machine-readable storage medium. In the present examples, the machine-readable storage medium may store instructions that, when executed by the module(s) 204, provides probability of clogging based on the identified input parameters.
[0060] In operation, the processing module 205 receives the data related to ingredients of molten steel at various stages of steel making, the steel making parameters, and the casting parameters. Based on the received data, the data processing module 205 determines a probability prediction index B using logit regression.
Probability prediction index ‘B’ = a1+ a2*(min (Bath P%, OLP P%)-Lfout P%)+ a3*if (Reblow=Yes Then 1 else 0)+ a4*OLP Al+ a5*if(LF top purging=Yes Then 1 else 0)+ a6*(OLP S%-LF S%)/OLP S%+ a7*LF Ca%+ a8*LF Ca%/LF Al%+ a9*(LF Slag FeO%+MnO%)+ a10*(LF N ppm-OLP N ppm)+ a11*(average tundish weight previous cast-tundish weight new cast at ladle open time)+ a12*(Superheat in °C at cast open)
Wherein a1, a2, a3,……a12 are constants.
[0061] Where, OLP is On-Line Purging station, LF is Ladle Furnace, P is phosphorus, S is Sulphur, Ca is calcium, Al is aluminium, FeO is Iron oxide, MnO is manganese oxide.
[0062] Further, the probability determining module 206 determines the probability ‘C’ using the probability prediction index ‘B’ in the shown in equation 1.
C = eB/(1+eB) ……………………………………equation 1
[0063] The probability determining module 206 determines probability in between 0 and 1 and displays the same on a display unit 208 coupled with the system 200 through the interface 202. Further, the determined probability ‘C’ is displayed at the time of heat open.
[0064] The determined probability of clogging ‘C’ in tundish 103 is displayed to the operator through the display unit 208 at the time of each heat open. Based on the determined probability C of clogging in the tundish 103, the operator treats the steel in the tundish 103 with calcium silicide (CaSi) to modify the alumina based inclusion into liquid inclusion phase of calcium aluminate that do not clog at SEN 105 refractory of the tundish 103. With the determination of clogging probability at the heat open, the operator gets sufficient time to take measure to avoid clogging in the tundish 103. With the present system 200, the tundish run smooth without clogging and efficiency of the casting system is improved with quality of casted steel.
[0065] FIG. 3 illustrates a method 300 for determining probability of clogging during continuous casting of steel, according to an implementation of the present disclosure. The order in which the method 300 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any appropriate order to carry out the method 300 or an alternative method. Additionally, individual blocks may be deleted from the method 300 without departing from the scope of the subject matter described herein.
[0066] At step 301, data related to ingredients of steel (both qualitative and quantitative) at various stages of steel making is received by the data processing module 205. The present method uses the ingredients of steel to know nature and extent of clogging. Accordingly, a suitable remedy for the same can be taken to eliminate or reduce or avoid clogging in the tundish 103.
[0067] At step 302, data related to steel making parameters is received by the data processing module 205. The steel making parameters encompass all primary and secondary steel making parameters having a bearing on steel cleanliness. The primary steel making parameters comprise Hot metal chemical analysis, Basic oxygen furnace (BOF) treatment end chemical analysis, Re-blow oxygen volume, blow end to tapping start duration, tapping additions, BOF slag carryover. The secondary steel making parameters comprise arcing duration, Bottom argon purging amount, top lance argon purging amount, Flux additives, Ferro-alloy additives, inclusion modification additives, slag chemical analysis, treatment duration, Liquid steel temperature at different treatment phases, change in liquid steel chemical composition during different treatment phases. The primary and the secondary steel making parameters are analyzed to determine their role in generation of alumina inclusion either by de-oxidation or re-oxidation process. After analyzing, the primary and the secondary steel making parameters which are responsible for generation of alumina based inclusion is considered for determining probability of clogging. The primary and the secondary steel making parameters, such as reblow oxygen value, top and bottom purging, etc., are selected to determine the probability of clogging in tundish.
[0068] At step 303, data related to casting parameters sensitive to clogging is received by the data processing module 205. The casting parameters comprise drop in tundish weight while ladle open, tundish weight during connection of heat, carryover slag volume from ladle to tundish, liquid steel temperature in tundish, and liquidus temperature of steel. The casting parameters are analyzed to determine their role in generation of alumina based inclusion either by de-oxidation or re-oxidation process. The casting parameters, such as average tundish weight (previous cast), tundish weight (new cast) at ladle open time and super heat at cast open are the main casting parameters used to determine the probability of clogging in tundish.
[0069] At step 304, the data processing module 205 process the received data of steel ingredients, steel making parameters and casting parameters which have a substantial effect on generation of clogging in the tundish using logit regression. The data processing module 205 process the identified responsible parameters using logit regression and determine the probability prediction index B based an empirical relation.
[0070] Based on the analysis of each parameter and its role in the generation of clogging in the tundish. A few parameters are selected, Steel making parameters such as Reblow from primary steel making unit; top purging from secondary steel making unit; average tundish weight previous cast, tundish weight new cast at ladle open time and superheat (oC) at cast open from caster unit. Steel ingredients such as Bath Phosphorus from primary steel making unit; OLP Phosphorus, Ladle Furnace Phosphorus, OLP Aluminium, Ladle Furnace, OLP Sulphur, Ladle Furnace Sulphur, Ladle Furnace calcium content, Ladle Furnace Aluminum content, FeO and MnO slag in Ladle Furnace, Ladle Furnace Nitrogen content in ppm, OLP Nitrogen content in ppm from secondary steel making unit are the identified responsible parameters for clogging in tundish during continuous casting of steel.
[0071] Sources of alumina can be categorized in two broad categories. One is when aluminium addition is done to deoxidize steel. Second as product of reoxidation of dissolved aluminium in steel by oxidized slag or by atmosphere. The selective parameters indicate one or other source of alumina based inclusion forming in steel. There occurrence either minimizes or maximizes inclusion generation and impact clogging at caster. Reblow practices increases dissolved oxygen of steel in furnace and causes higher FeO in slag. Bottom purging is used to remove inclusions from steel and desirable, the use of top purging is ineffective in inclusion floatation from bottom to top in the ladle and increases the turbulence at steel and slag interface resulting higher inclusion in steel. Phosphorous content at different station indicates the possibility of carryover FeO rich slag from furnace to ladle, if there is phosphorous reversal in steel observed at secondary steel making it suggest furnace slag carryover. The Olp Al indicates deoxidized condition of steel after tapping, achieving higher aluminium content at before ladle furnace gives sufficient time for inclusion to float out of steel and join slag. Extent of desulphurization at LF indicates the presence of good reducing slag for most of the ladle processing time that’s reduces re-oxidation from slag. FeO and MnO content of LF slag indicates the finished oxidizing potential of slag and good for reduced reoxidation in further process of casting. Nitrogen content at OLP and LF indicates possibility of atmosphere contact with steel during LF processing, higher N pick up at LF indicates reoxidation occurring at LF. LF Calcium and aluminium content is controlled at LF to keep the inclusions in desired form. Higher superheat in tundish i.e. temperature of steel above liquidus gives better opportunity for inclusions to be in liquid phase and easier inclusion floatation in steel. Change in tundish weight is the reduction in weight during heat change in sequence, lower weight indicates lowering retention time of incoming steel from next ladle and higher inclusions going to SEN at that instant of time.
[0072] An empirical relation between the identified parameters, determined in step 301, 302 and 303 is derived using a logit regression. The empirical relation between the parameters produces a probability prediction index ‘B’ which is further used to determine the probability of clogging in tundish 103. The empirical relation derived from the identified parameters is shown below:
B = a1+ a2*(min (Bath P%, OLP P%)-Lfout P%)+ a3*if (Reblow=Yes Then 1 else 0) + a4*OLP Al+ a5*if(LF top purging=Yes Then 1 else 0)+ a6*(OLP S%-LF St%)/OLP S%+ a7*LF Ca%+ a8*LF Ca%/LF Al%+ a9*(LF Slag FeO%+MnO%)+ a10*(LF N ppm-OLP N ppm)+ a11*(average tundish weight previous cast-tundish weight new cast at ladle open time)+ a12*(Superheat in °C at cast open)
Wherein a1, a2, a3,……a12 are constants.
[0073] At step 305, probability of clogging ‘C’ is determined by the probability determining module 206 using the determined probability prediction index ‘B’ via relation eB/(1+eB). The determined probability is displayed at the display unit 208 at the time of each heat open.
[0074] The present method displays probability of clogging at the time of heat open to take corrective action timely during continuous casting of steel to avoid sudden stopper drop and casting outage. This enhance the overall efficiency of the casting process and improve the production of steel. Further, the degradation of steel due to entrapment of alumina based inclusions in steel during casting process is eliminated.
[0075] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0076] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0077] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.