FORM 2
THE 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 SHOWER CLEANING OF LADLE SHROUD AND A METHOD OF SUCH CLEANING
2 APPLICANT (S)
Name : JSW Steel Limited.
Nationality : An Indian Company.
Address : Jindal Mansion, 5-A, Dr. G. Deshmukh Marg, State of Maharastra, India. Mumbai - 400 026,
3 PREAMBLE TO THE DESCRIPTION
COMPLETE
The following specification be performed. particularly describes the invention and the manner in which it is to

FIELD OF THE INVENTION
The present invention relates to a system for oxygen shower cleaning of refractory ladle shroud used for metal teeming from ladle to tundish and to a method for carrying out said cleaning of slag and metal sticking on the shroud surface involving oxygen shower. More importantly, the invention is directed to a system and method for shower cleaning of ladle shroud which would minimize time and also avoid fumes and splashes during shroud cleaning. Advantageously, the present method of shower cleaning of shroud involving the Oxygen shower is adapted such as to clean whole surface area of shroud uniformly in less time eliminating the problems of metal splashing and generation of hazardous fumes polluting the work environment. The system of shroud cleaning is further provide with safety means such as to make the cleaning operation safe and operator friendly. This arrangement prevents the exposure of operators to the red hot shroud and also avoids possibilities of contamination of steel. The method of shroud cleaning is thus safe as no metal splashes is encountered by the operator due to the favourable and selective disposition of the shroud during cleaning and the slag disposal is off-line into a container. The system of the invention is further adapted for fume extraction to avoid fumes coming out. The system and method of oxygen-shower cleaning of ladle shroud of the invention thus provides for a safe, fast , environment friendly as well as user friendly method and avoids delay in ladle opening in sequence operation, reducing the ladle change over time to less than 2 minutes, while ensuring high quality avoiding contamination and thus improving productivity in continuous casting.
BACKGROUND ART
It is known in the art of Continuous casting in steel plants, teeming of liquid metal is carried out in short mould with false bottom, through which partially solidified ingot is continuously drawn at the same rate at which metal is being poured. To maintain stringent quality of cast steel product and a close control on the desired chemistry, closed continuous casting is the best practice that is directed to a method wherein no metal is exposed to atmosphere. Conventionally, to achieve such closed casting practice, liquid steel is teemed ladle to tundish, through a refractory based Ladle shroud. The Ladle Shroud is usually a ceramic tube having selective geometric configuration manufactured from isostatically pressed alumina graphite adapted for immediate connection to the ladle


slide gate nozzle providing maximum protection to the steel stream from ladle to tundish, against oxidation from the atmosphere and minimizing steel splashing.
The shroud used for such pupose needs to be cleaned to remove the sticking slag and metal after every heat using oxygen for immediate re-use during sequence casting operations.
Conventional cleaning practices for the ladle shroud involves use of straight lance keeping the shroud in slant position over the tundish cover thereby resulting in only one point and non-uniform cleaning of shroud surfaces which also normally takes more time and also contaminates the steel in tundish due to slag entrapment detached from shroud wall during cleaning. This method of cleaning already in practice also involve a operational hazard due to metal splashing on the operator while carrying out oxygen lance cleaning. Equipments installed in the vicinity are also exposed to metal splashes, in opposite side of the slant of shroud, running the risk of damage. In addition, open cleaning also generates iron fumes, which pollute the work environment. This method of cleaning takes more time and some times becomes critical, due to delay in ladle opening in sequence operations.
There has been therefore a continuous need for an improved method of cleaning of inner walls of ceramic ladle shroud used in continuous steel casting, capable for providing means for fast and thorough as well as uniform cleaning of the entire surface of the shroud in a fast, safe and user friendly manner and also to ensure desired quality of steel obtained in tundish free of oxidation or contamination due to slag entrapment or the like, ensuring enhanced productivity reducing cleaning/ladle change over time, in between the successive heats during sequence casting operation.
OBJECTS OF THE INVENTION
It is thus the basic object of the present invention to provide a system and method of shower cleaning involving oxygen shower such as to clean the whole shroud surface free of slag or metal sticking, at lesser time reducing thereby the ladle change over time to less than 2 minutes and eliminating the risks of metal splashing or the hazards relating to generation of obnoxious fumes or possibility of damaging equipments in the vicinity of cleaning site, and thus improving the productivity of the continuous casting plant.


A further object of the present invention directed to a system and method of shower cleaning of shroud which would favour faster and uniform cleaning in a user friendly and safe manner, without exposing the operator to the red hot shroud.
A still further object of the present invention is directed to a system and method of shower cleaning of shroud which would ensure superior quality of steel obtained in tundish, free of any contaminants due to slag entrapment.
Yet another object of the present invention is directed to a system and method of shower cleaning of shroud free of problems of fume emission and also ensuring safety of the operator during the cleaning process.
A still further object of the present invention directed to a system and method of shower cleaning of shroud which would favour the shroud cleaned thoroughly from slag and or metal sticking to its wall in minimum time and thereby making the shroud ready for re-use immediately after every heat by reducing the ladle change over time and favor continuous casting in sequence casting operation without delay or interruption.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided a system for shower cleaning of ladle shroud comprising:
oxygen shower cooperatively disposed with respect to the shroud to be cleaned ,said shroud disposed vertically such that the oxygen shower is adapted for injection straight through the vertical shroud for uniform shroud cleaning and slag disposal is off-line, a slag collecting container disposed at the lower end of the shroud for safe collection of the discharged slag.


Another aspect of the present invention is directed to said system for shower cleaning of ladle shroud comprising a shroud cover.
A further advantageous aspect of the present invention is directed to a system for shower cleaning of ladle shroud comprising a fume exhaust unit cooperatively disposed to favour safe extraction of fumes generated during the shroud cleaning.
Another aspect of the system for shower cleaning of ladle shroud of the present invention includes said fume exhaust unit comprising fume exhaust motor attached to the vertical arrangement through duct thereby favouring entrapping the fumes for effective extraction.
A still further aspect of the present invention is directed to a method of shower cleaning of ladle shroud using the system comprising:
providing the shroud to be cleaned vertical and off-line;
providing a source of oxygen shower at the top end of the shroud and a slag
collection unit at the lower end of the shroud; and
allowing the flow of oxygen shower vertically through the shroud for uniform cleaning of the shroud and collection of the slag in the slag collection unit.
A still further aspect of the present invention is directed to said method of shower cleaning of ladle shroud using the system wherein the said fume exhaust unit is operated to extract the fumes generated during the cleaning process through the fume exhaust.


According to another favored aspect of the present invention directed to said method of shower cleaning of ladle shroud using the system wherein the ladle change over time after cleaning is less than 2 mins.
A still further aspect of the present invention is directed to said method of shower cleaning of ladle shroud using the system wherein the operator and/or equipments are protected by maintaining the shroud well covered during the cleaning process.
According to yet another aspect of the method of shower cleaning of ladle shroud using the system of the present invention, wherein iron fumes are sucked and discharges in the cooling chamber.
The present invention and its objects and advantages are described in greater details with reference to the accompanying non-limiting illustrative figures.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1: illustrates the features of the method and devices used in the conventional cleaning process of ladle shroud;
Figure 2: illustrates the novel features of the faster cleaning method by oxygen shower cleaning of ladle shroud according to the present invention, ensuring quality and safety in sequence casting of steel.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING FIGURES:
As already described, the ladle shroud is the ceramic duct/tube portion known in the art of continuous casting of steel, that is used to trans port liquid steel from the ladle to tundish


for advantageous closed/non-contaminating method of steel casting eliminating the risk of oxidation of steel by way of exposure to atmospheric air/oxygen or slag entrapment.
A high quality standard is expected while 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. To maintain stringent quality of cast steel product and a close control on the desired chemistry, closed continuous casting is the best practice that is directed to a method wherein no metal is exposed to atmosphere. Conventionally, to achieve such closed casting practice, liquid steel is teemed ladle to tundish, through a refractory based Ladle shroud. The Ladle Shroud is usually a ceramic tube having selective geometric configuration manufactured from isostatically pressed alumina graphite adapted for immediate connection to the ladle slide gate nozzle providing maximum protection to the steel stream from ladle to tundish, against oxidation from the atmosphere and minimizing steel splashing.
The present invention, thus deals with the problem of cleaning of the ladle shroud in fast and safe manner to avoid operational hazard on one hand and on the other hand favor fast and through uniform cleaning of the ceramic shroud immediately after each heat is over, such as to make it ready for re-use without any undesirable delay in continuous casting operation, and thus improving the productivity and quality.
Reference is now invited to the accompanying Figure 1 that illustrates the conventional method and equipments used for cleaning ladle shroud in existing practice. It is apparent from the Figure 1, that the conventional cleaning practices for the ladle shroud involves use of straight lance keeping the shroud in slant position over the tundish cover thereby resulting in only one point and non-uniform cleaning of shroud surfaces which also normally takes more time and also contaminates the steel in tundish due to slag entrapment detached from shroud wall during cleaning. This method of cleaning already in practice also involve a operational hazard due to metal splashing on the opposite side of lance causing injury to operator while carrying out oxygen lance cleaning. Equipments installed in the vicinity are also exposed to metal splashes, in opposite side of the slant of shroud, running the risk of damage. In addition, open cleaning also generates iron fumes, which pollute the work environment. The conventional method of cleaning takes more time and some times becomes critical, due to delay in ladle opening in sequence operations.


Reference is now invited to accompanying Figure 2 illustrating the shower cleaning of the refractory ladle shroud according to the present invention. As compared to the conventional cleaning practice, the present invention advantageously use Oxygen shower cleaning of Refractory ladle shroud introduced to reduce the cleaning and also the ladle changeover time. As apparent from the accompanying Figure 2, the present invention involve practice of oxygen shower cleaning is introduced for refractory walls of ladle shroud which cleans the whole surface area of the shroud at a very fast speed and favorably in less than 1 min and thus the ladle change over is possible in less than 2 minutes time. In the present method using a new system, the shroud by keeping it vertical and cleaned with the use of oxygen shower, which cleans the shroud uniformly. A separate arrangement for covering the shroud and collecting the slag in a container was made to make cleaning operation user friendly and safe. Such an arrangement prevents the exposure of operators to the red hot shroud and avoids contamination of steel obtained in tundish by way of slag entrapment. This practice is not only safe as no metal splashes are encountered by the operator and the shroud is held vertical and carrying the detached metal/slag vertically downward through a ducting. Also the slag disposal is off-line into a container keeping the operator free of any occupational hazard due to hot metal splash or fumes evolving. An additional fume extraction system consisting of a fume exhaust motor attached to the vertical arrangement through a duct, to avoid fumes coming out. Iron fumes generated is thus sucked in and discharged by the system in the cooling chamber, maintaining the work environment clean and safe.
It is thus possible by way of this invention to provide for a method for faster and uniform cleaning of inner walls of the refractory shroud used to carry liquid metal from ladle to tundish, making it free of any metal/slag sticking to the inner wall of the shroud, and thereby reducing the ladle change over time and superior quality of steel in sequence casting avoiding contamination due to slag entrapment or the like. The present invention also provides for the system to carry out such method involving cover and container to restrict hot metal splashing and a fume extraction device to collect iron fumes and transport the same to cooling chamber through duct, ensuring safety of operator and equipments in the vicinity of shroud cleaning area. The present method is thus fast and capable of providing superior quality steel in tundish prior to casting with minimized ladle change over time to less than 2minutes, favoring improving productivity in sequence casting operations in continuous casting plant.


WE CLAIM:
1. A system for shower cleaning of ladle shroud comprising:
oxygen shower cooperatively disposed with respect to the shroud to be cleaned, said shroud disposed vertically such that the oxygen shower is adapted for injection straight through the vertical shroud for uniform shroud cleaning and slag disposal is off-line, a slag collecting container disposed at the lower end of the shroud for safe collection of the discharged slag.
2. A system for shower cleaning of ladle shroud as claimed in claim 1 comprising a shroud cover .
3. A system for shower cleaning of ladle shroud as claimed in anyone of claims 1 or 2 comprising a fume exhaust unit cooperatively disposed to favour safe extraction of fumes generated during the shroud cleaning.
4. A system for shower cleaning of ladle shroud as claimed in claim 3 wherein said fume exhaust unit comprises fume exhaust motor attached to the vertical arrangement through duct thereby favouring entrapping the fumes for effective extraction.
5. A method of shower cleaning of ladle shroud using the system as claimed in anyone of claims 1 to 4 comprising:
Providing the shroud to be cleaned vertical and off-line;
Providing a source of oxygen shower at the top end of the shroud and a slag
collection unit at the lower end of the shroud; and


Allowing the flow of oxygen shower vertically through the shroud for uniform cleaning of the shroud and collection of the slag in the slag collection unit.
6. A method of shower cleaning of ladle shroud using the system as claimed in claim 5 wherein the said fume exhaust unit is operated to extract the fumes generated during the cleaning process through the fume exhaust.
7. A method of shower cleaning of ladle shroud using the system as claimed in anyone of claims 5 or 6 wherein the ladle change over time after cleaning is less than 2 mins.
8. A method of shower cleaning of ladle shroud using the system as claimed in anyone of claims 5 to 7 wherein the operator and/or equipments are protected by maintaining the shroud well covered during the cleaning process.
9. A method of shower cleaning of ladle shroud using the system as claimed in anyone of claims 5 to 8 wherein iron fumes are sucked and discharges in the cooling chamber.
10. A system for shower cleaning of ladle shroud and a method for shroud cleaning substantially as hereindescribed and illustrated with reference to the accompanying figures.




ABSTRACT
TITLE: A SYSTEM FOR SHOWER CLEANING OF LADLE SHROUD AND A METHOD OF SUCH CLEANING.
A system for oxygen shower cleaning of refractory ladle shroud used for metal teeming from ladle to tundish and to a method for carrying out said cleaning of slag and metal sticking on the shroud surface involving oxygen shower. More importantly, the invention is directed to a system and method for shower cleaning of ladle shroud which would minimize time and also avoid fumes and splashes during shroud cleaning. Advantageously, the present method of shower cleaning of shroud involving the Oxygen shower is adapted such as to clean whole surface area of shroud uniformly in less time eliminating the problems of metal splashing and generation of hazardous fumes polluting the work environment. The system and method of oxygen-shower cleaning of ladle shroud thus provides for a safe, fast, environment friendly method and avoids delay in ladle opening in sequence operation, reducing the ladle change over time to less than 2 minutes while ensuring high quality and improved productivity. Figure 2.