FORM 2THE PATENT ACT 1970 (39 OF 1970) &The Patent Rules, 2003COMPLETE SPECIFICATION(See Section 10 and Rule 13)
1 TITLE OF THE INVENTION :
A SYSTEM FOR PRE-HEATING OF SUBMERGED ENTRY NOZZLE (SEN) AND A METHOD THEREOF FOR SEN HEATING.
2 APPLICANT (S)
Name : JSW Steel Limited.
Nationality : An Indian Company.
Address : Jindal Mansion, 5-A, Dr. G. Deshmukh Marg, Mumbai State of Maharastra, India. - 400 026,
3 PREAMBLE TO THE DESCRIPTION
COMPLETE
The following specification particularly describes the invention and the manner in be performed. which it is to

FIELD OF THE INVENTION
The present invention relates to a system for preheating of the Submerged Entry Nozzle (SEN) and in particular to the system for preheating of the submerged entry nozzle utilizing the heat source for heating the tundish and a method thereof, prior to casting of liquid metal from ladle for continuous casting of ingot. More particularly, the present invention is directed to a system of preheating of the submerged entry nozzle involving the COREX gas flame used for preheating of the tundish. The COREX gas flame from inside of tundish is capable to preheat the SEN sufficiently. Advantageously, the system would favor enhancement of SEN preheating by venturi effect to desired preheat temperature in the order of 1200°C and thereby avoid initial thermal shock or skull formation and also tendency of SEN cracking when liquid metal is teemed into the mould. The method of tundish and SEN preheating simultaneously using the same heat source is simple and economic avoiding use of expensive additional fuel such as LPG, and ensure operational safety avoiding risk of fire or leakage/waste of costly gas or reduced burner life due to intense heat.
BACKGROUND ART
It is well known in the field of Continuous casting involves teeming of liquid metal in short mould with false bottom, through which partially solidified ingot is continuously drawn at the same rate at which metal is being poured. It is also a desirable factor for maintaining desired quality of cast product, closed continuous casting is the best practice whereby no metal is exposed to atmosphere. This is conventionally achieved by providing a closed passage called a shroud or nozzle that transport the liquid steel from the ladle to tundish; also the metal is teemed into the mould through a refractory based submerged entry nozzle (SEN), to ensure that at no point the liquid steel gets exposed to the atmosphere before being cast into ingots. A stopper in tundish is used to control the flow of molten steel from the tundish to the mould. Such a stopper comprises a monoblock refractory body having a longitudinal through bore of selective dimension in its body. Each time a new heat is being cast afresh , the tundish and the SEN have to be preheated to a temperature of 1200°C before casting, to absorb the initial thermal shock of liquid steel temperature and minimize the formation of a skull. At JSW Steel Ltd, tundish preheating in the existing process was done using COREX gas while SEN preheating was being done


using LPG fired in suitable burners. Tundish is heated using top burners and COREX gas, whereas the SEN is heated through a separate burner from bottom for about 3 hrs before the start of casting.
It is a common experience in the conventional preheating of SEN/tundish that the LPG as fuel is not only hazardous and unsafe to use in open air, but also increasing the chances of fire and loss of costly LPG due to hose leakage. The use of LPG also tends to reduce the life of burners used for preheating of SEN due to intense heat generation during preheating. The existing practice further makes the conditions un-favorable for operators. In addition, LPG being a costly fuel which also adds to the cost of production.
There has been therefore a continuous need to develop a simple and cost effective method for preheating of SEN and the tundish prior to continuous casting in mould which would overcome the problems experienced in the prior practice in the relevant field, avoiding the risks of fire and unsafe operating condition, burner damage by intense heat loss due to leakage of LPG, increased cost due to LPG consumption and/or loss, used for SEN preheating purpose. It is desirable that a new method would economize cost of inputs and thereby reduce cost of production while ensuring safe and operator friendly work atmosphere conducting preheating of both tundish and nozzle in an energy efficient manner, and thus would improve productivity in continuous casting plant in steel industries.
OBJECTS OF THE INVENTION
Thus the basic object of the present invention is directed to a system for preheating of tundish and SEN prior to teeming of liquid steel in mould and a method of said preheating using the heat source for preheating of the tundish with high efficiency avoiding use of further expensive heat source for heating of the SEN and in the process also ensuring safe operation avoiding hazards due to, gas leakage, fire or burner damage due to over heating of SEN.
A further object of the present invention is directed to a system and a method using such system of preheating of tundish as well as SEN by a single COREX gas source for heating


of the SEN from inside of tundish which would favour effective heat for SEN preheating to desired temperature.
A still further object of the present invention is directed to a system and method of preheating of SEN during tundish preheating with COREX gas flame from inside in a manner such that the COREX heat to SEN is further enhanced by way of a venturi effect to attain the desired temperature prior to teeming/casting in mould, in a steady and uniform heating at less time.
Another object of the present method directed to a method of preheating of tundish and SEN by selective use of COREX gas carried with forced air draft thereby eliminating occurrence of SEN cracking.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided a system for pre-heating of submerged entry nozzle (SEN) comprising:
burner means for pre-heating of tundish;
a stopper block operatively connected to said submerged entry nozzle;
means for passing air through said stopper block for directing the heat/flame of heating of said tundish to said submerged entry nozzle whereby the tundish and the submerged entry nozzle can be preheated using the same source of preheating the tundish.
A further aspect of the present invention is directed to said system for pre-heating of submerged entry nozzle (SEN) wherein said burner means for pre-heating of tundish comprise Corex gas based burner means.


A still further aspect of the present invention is directed to said system for pre-heating of submerged entry nozzle (SEN) wherein Corex gas flame from inside the tundish is used for pre-heating said submerged entry nozzle.
Another further aspect of the present invention is directed to said system for pre-heating of submerged entry nozzle (SEN) comprising means for supplying draft of compressed air through mono-block stopper for said pre-heating of the tundish.
According to yet another aspect of the present invention the same is directed to said
system for pre-heating of submerged entry nozzle (SEN) wherein said passage of air
through the monoblock stopper is adapted to enhance the submerged entry nozzle pre
heating by venturi effect to desired preheat temperature.
According to another aspect of the present invention the same is directed to a method for pre-heating of submerged entry nozzle (SEN) comprising:
pre- heating the tundish by burning Corex gas;
passing air through said stopper block for directing the heat/flame of heating of said tundish to said submerged entry nozzle whereby the tundish and the submerged entry nozzle are preheated using the same source of Corex gas for heating the tundish.
The present invention and its objects and advantages obtained through the system for pre-heating of submerged entry nozzle (SEN) according to the invention and its use in pre-


heating of the tundish and the submerged entry nozzle is described in further details with reference to non-limiting accompanying figures.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: is the illustration of the system for the method of conventional preheating involving COREX gas and burners for tundish heating and LPG with burner for SEN preheating.
Figure 2: is the illustration of the system for implementing the method of preheating of both tundish by COREX gas through burners at top of tundish and SEN with flame and compressed air draft from inside tundish through refractory mono-block stopper, according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING FIGURES
The present invention relates to a method of preheating of the Submerged Entry Nozzle (SEN) and the tundish and an improved system to carryout said method, prior to pouring of liquid metal from ladle for continuous casting of ingot in short mould with short bottom. More particularly, the present invention is directed to a method of preheating of tundish by the use of COREX gas flame and the SEN is self-heated with COREX gas from inside during tundish preheating.
As already described, the conventional tundish and SEN preheating practice involves COREX gas as fuel for preheating of tundish by burning the gas through selectively located and in selective number of burners of preferred configuration on the top of tundish cover. Each time a new heat is being cast afresh in short mould with false bottom to be continuously cast into ingots at synchronus speed as of pouring , the tundish and the SEN essentially need to be preheated to a temperature of 1200°C before casting, to absorb the initial thermal shock of liquid steel temperature and minimize the formation of a skull. Reference is first invited to accompanying Figure 1, wherein the conventional method of


tundish and SEN preheating prior to start of continuous casting, has been illustrated. It is clearly apparent from the Figure 1 that the SEN is heated by a separate burner mounted on the nozzle and is receiving heat by the burning of LPG in this isolated burner. The process is thus involving the complexity of providing separate burners and supply of separate fuel gas for heating of the tundish and the SEN such as the COREX for the tundish and LPG for preheating of the SEN. Moreover, separate burners are used for the tundish preheating and the heating of SEN before casting commences. The existing process is thus suffering from the disadvantage and limitations due to leakage of costly LPG from the pipelines and the tendency of firing in the working area and thus creating operator's hazard and risk while at work. The SEN heating burners are also subjected to rapid wearing out and damage due to the intense heat during burning of LPG for attaining desired temperature before casting is started. Moreover, LPG being a costly gas used as fuel for preheating of SEN, makes the cost of input and thereby the cost of production higher. The present method is therefore an invention directed to utilizing the COREX gas as fuel substituting the costly LPG gas and also eliminates the use of SEN preheating burner and thus making the process simple, safe, reliable and less costly.
Reference is now invited to the accompanying Figure 2 that illustrates the system for implementing the method according to the invention, wherein COREX gas is used to preheat both the Tundish and the SEN prior to molten metal teeming in short mould with false bottom/ continuous casting. It is clearly apparent from said Figure 2 that the SEN preheating is carried out by the COREX gas, totally eliminating LPG usage and the SEN is self-heated during tundish preheating with COREX gas flame from inside. With the use of high efficiency COREX gas, the flame directed to SEN from inside the tundish, is sufficient to preheat SEN to desired temperature in the range of 1200°C. Importantly, provision of a draft of compressed air through the passage provided in the mono-block stopper further enhances the SEN preheating to the desired temperature favoring smooth continuous casting operation when started. The system of the present invention making advantageous use of this self-preheating of the SEN from tundish heat by creating in combination compressed air draft which drives the COREX gas flames from the tundish top burners through the passage in the monoblock stopper which enhances the SEN preheating by venturi effect to said desired preheat temperature. Continuous casting plant operating on the present method and the system thereof, is not subjected to any SEN cracking, before start of cast, after its implementation and thereby reducing costs and improving productivity, free of any major constraint relating to maintenance/operation. The invention


is also capable of substantial monetary and eliminated the chances of fire/line leakage, by eliminating use of costly LPG.
It is thus possible by way of this invention to achieve a simple, safe and cost effective method for preheating of the tundish and the SEN before continuous casting/pouring of liquid steel from ladle to tundish is commenced for continuous closed casting in short mould with false bottom to produce good quality ingots. The method of the invention is adapted to use COREX gas for preheating both tundish and the SEN, eliminating use of expensive LPG and thus effecting substantial cost saving to the tune of about Rs 24 lacs / annum and prevent occurrence of fire and/or gas leakages completely and also ensuring improved working condition for operators in CCP shop in large integrated steel plants, thus improving productivity and favoring wide industrial application.


WE CLAIM:
1. A system for pre-heating of submerged entry nozzle (SEN) comprising:
burner means for pre-heating of tundish;
a stopper block operatively connected to said submerged entry nozzle;
means for passing air through said stopper block for directing the heat/flame of preheating of said turndish to said submerged entry nozzle whereby the turndish and the submerged entry nozzle can be preheated using the same source of heating the turndish.
2. A system for pre-heating of submerged entry nozzle (SEN) as claimed in claim 1
wherein said burner means for pre-heating of turndish comprise Corex gas based
burner means.
3. A system for pre-heating of submerged entry nozzle (SEN) as claimed in anyone of claims 1 or 2 wherein Corex gas flame from inside the turndish is used for pre-heating said submerged entry nozzle.
4. A system for pre-heating of submerged entry nozzle (SEN) as claimed in anyone of claims 1 to 3 comprising means for supplying draft of compressed air through mono-block stopper for said pre-heating of the turndish.
5. A system for pre-heating of submerged entry nozzle (SEN) as claimed in anyone of claims 1 to 4 wherein said passage of air through the monoblock stopper is adapted to


enhance the submerged entry nozzle pre-heating by venturi effect to desired preheat temperature.
6. A method for pre-heating of submerged entry nozzle (SEN) comprising:
pre-heating the turndish by burning Corex gas;
passing air through said stopper block for directing the heat/flame of preheating of said turndish to said submerged entry nozzle whereby the turndish and the submerged entry nozzle are preheated using the same source of Corex gas for heating the turndish.
7. A system for pre-heating of submerged entry nozzle (SEN) and its use in preheating of the turndish and the submerged entry nozzle substantially as hereindescribed and illustrated with reference to the accompanying figures.

ABSTRACT
TITLE: A SYSTEM FOR PRE-HEATING OF SUBMERGED ENTRY NOZZLE (SEN) AND A
METHOD THEREOF FOR SEN HEATING.
A system for preheating of tundish and the Submerged Entry Nozzle (SEN) prior to ladle teeming ingot and a method for said preheating. More particularly, the present invention is directed to a system and method of preheating of tundish by the use of COREX gas flame and the SEN is self-heated with COREX gas from inside during tundish preheating. The COREX gas flame from inside of tundish is capable to preheat the SEN sufficiently. Compressed air draft provided through mono-block stopper in tundish further enhance the SEN preheating efficiency. The Self-preheating of the SEN from tundish heat by passing the hot air through the refractory mono-block stopper favors enhancement of SEN preheating by venturi effect to desired preheat temperature to avoid initial thermal shock or skull formation and also SEN cracking when liquid metal is teemed. The method of tundish and SEN preheating is simple , safe and less expensive having longer burner life. Figure 2.