Claims
- 1. A method for blowing oxygen into molten iron in a converter, in an oxygen refining process wherein oxygen is blown into the converter using a top-blown lance having a Laval nozzle installed at the tip of the top-blown lance, and wherein the Laval nozzle has a back pressure of the nozzle Po(kPa) satisfying the following formula with respect to a oxygen-flow-rate FhS(Nm3/hr) per hole of the Laval nozzle determined from the oxygen-flow-rate FS(Nm3/hr) in a high carbon region in a peak of decarburization and a throat diameter Dt (mm),Po=FhS/(0.00465·Dt2) the Laval nozzle has an exit diameter De satisfying the following formula with respect to the back pressure of the nozzle Po(kPa), an ambient pressure Pe(kPa), and said throat diameter Dt (mm): De2≦0.23×Dt2/{(Pe/Po)5/7×[1−(Pe/Po)2/7]}.
- 2. The method according to claim 1, wherein said exit diameter De of the Laval nozzle satisfies the following formula with respect to the back pressure of the nozzle Po(kPa), the ambient pressure Pe(kPa), and said throat diameter Dt(mm):De2≦0.18×Dt2/{(Pe/Po)5/7×[1−(Pe/Po)2/7]1/2}.
- 3. The method according to claim 2, wherein said exit diameter De of the Laval nozzle satisfies the following formula with respect to the back pressure of the nozzle Po(kpa), the ambient pressure Pe(kPa), and said throat diameter Dt (mm):0.15×Dt2/{(Pe/Po)5/7×[1−(Pe/Po)2/7]1/2}≦De2≦0.18Dt2/{(Pe/Po)5/7×[1−(Pe/Po)2/7]1/2}.
- 4. The method according to claim 1, wherein said top-blown lance has multiple Laval nozzles, and at least one of those Laval nozzles satisfies conditions of the following two formulas:Po=FhS/(0.00465·Dt2) De2≦0.23×Dt2/{(Pe/Po)5/7×[1−(Pe/Po)2/7]1/2}.
- 5. The method according to claim 4, wherein said top-blown lance has the multiple Laval nozzles, and at least one of those Laval nozzles satisfies the conditions of the following two formulas:Po=FhS/(0.00465·Dt2) De2≦0.185×Dt2/{(Pe/Po)5/7×1−(Pe/Po)2/7]1/2}.
- 6. The method according to any one of claims 1 to 5, wherein the oxygen blowing is carried out at an amount of slag of less than 50 kg per ton of molten steel.
- 7. The method according to claim 6, wherein the oxygen blowing is done at the amount of the slag of less than 30 kg per ton of the molten steel.
- 8. The method according to any one of claims 1 to 5, whereinsaid Laval nozzle has the back pressure of the nozzle Poo(kpa) satisfying the following formula with respect to the oxygen-flow-rate FhM(Nm3/hr) per hole of the Laval nozzle determined from the oxygen-flow-rate FM(Nm3/hr) in the low carbon region in an end of the blow and said throat diameter Dt (mm), Poo=FhM/(0.00465·Dt2) said exit diameter De has a ratio (De/Deo) of 1.10 or less to an optimum exit diameter Deo (mm) obtained from the back pressure Poo(kPa), the ambient pressure Pe(kPa), and said throat diameter Dt(mm) according to the following formula: Deo2≦0.259×Dt2/{(Pe/Poo)5/7×[1−(Pe/Poo)2/7]1/2}.
- 9. A method for blowing oxygen into molten iron in a converter, in an oxygen refining process wherein oxygen is blown into the converterwherein said Laval nozzle has the back pressure of the nozzle Poo(kPa) satisfying the following formula with respect to the oxygen-flow-rate FhM(Nm3/hr) per hole of the Laval nozzle determined from the oxygen-flow-rate FM(Nm3/hr) in the low carbon region in the end of the blow and the throat diameter Dt (mm), Poo=FhM/(0.00465·Dt2) said exit diameter De of the Laval nozzle has the ratio (De/Deo) of 0.95 or less to the optimum exit diameter Deo(mm) obtained from the back pressure Poo(kPa), the ambient pressure Pe(kPa), and said throat diameter Dt(mm) according to the following formula: Deo2=0.259×Dt2/{(Pe/Po)5/7×[1−(Pe/Poo)2/7]1/2}.
- 10. The method according to claim 9, wherein said top-blown lance has the multiple Laval nozzles, and at least one of those Laval nozzles satisfies the conditions of the following two formulas:Poo=FhM/(0.00465·Dt2) Deo2=0.259×Dt2/{(Pe/Poo)5/7×[1−(Pe/Poo)2/7]1/2}.
- 11. The method according to claim 9, wherein the oxygen blowing is carried out at the amount of the slag less than 50 kg per ton of the molten steel.
- 12. The method according to claim 11, wherein the oxygen blowing is done at the amount of the slag less than 30 kg per ton of the molten steel.
- 13. A top-blown lance for blowing oxygen in a converter, the top-blown lance having the Laval nozzle installed on the tip,characterized in that said Laval nozzle has the back pressure of the nozzle Po(kPa) satisfying the following formula with respect to the oxygen-flow-rate FhS(Nm3/hr) per hole of the Laval nozzle determined from the oxygen-flow-rate FS(Nm3/hr) in the high carbon region in the peak of the decarburization and the throat diameter Dt(mm), Po=FhS/(0.00465·Dt2) the exit diameter De of the Laval nozzle satisfies the following formula with respect to the back pressure of the nozzle Po(kpa), the ambient pressure Pe(kPa), and said throat diameter Dt (mm): De2≦0.23×Dt2/{(Pe/Po)5/7×[1−(Pe/Po)2/7]1/2}.
- 14. A top-blown lance for blowing oxygen in a converter, the top-blown lance having the Laval nozzle installed on the tip,characterized in that said Laval nozzle has the back pressure of the nozzle Poo(kPa) satisfying the following formula with respect to the oxygen-flow-rate Fhx (Nm3/hr) per hole of the Laval nozzle determined from the oxygen-flow-rate FM(Nm3/hr) in the low carbon region in the end of the blow and the throat diameter Dt(mm), Poo=FhM/(0.00465·Dt2) said exit diameter De of the Laval nozzle has the ratio (De/Deo) of 0.95 or less to the optimum exit diameter Deo(mm) obtained from the back pressure Poo(kpa), the ambient pressure Pe(kPa), and said throat diameter Dt(mm) according to the following formula: Deo2=0.259×Dt2/{(Pe/Poo)5/7×[1−(Pe/Poo)2/7]1/2}.
- 15. The method according to claim 6, whereinsaid Laval nozzle has the back pressure of the nozzle Poo(kPa) satisfying the following formula with respect to the oxygen-flow-rate FhM(Nm3/hr) per hole of the Laval nozzle determined from the oxygen-flow-rate FM(Nm3/hr) in the low carbon region in an end of the blow and said throat diameter Dt(mm), Poo=FhM/(0.00465·Dt2) said exit diameter De has a ratio (De/Deo) of 0.10 or less to an optimum exit diameter Deo(mm) obtained from the back pressure Poo(kPa), the ambient pressure Pe(kpa), and said throat diameter Dt(mm) according to the following formula: Deo2=0.259×Dt2/{[(Pe/Poo)5/7×[1−(Pe/Poo)2/7]1/2}.
- 16. The method according to claim 7, whereinsaid Laval nozzle has the back pressure of the nozzle Poo(kPa) satisfying the following formula with respect to the oxygen-flow-rate FhM(Nm3/hr) per hole of the Laval nozzle determined from the oxygen-flow-rate FM(Nm3/hr) in the low carbon region in an end of the blow and said throat diameter Dt(mm), Poo=FhM/(0.0046·Dt2) said exit diameter De has a ratio (De/Deo) of 0.10 or less to an optimum exit diameter Deo(mm) obtained from the back pressure Poo(kPa), the ambient pressure Pe(kPa), anti said throat diameter Dt(mm) according to the following formula: Deo2=0.259×Dt2/{(Pe/Poo)5/7×[1−(Pe/Poo)2/7]1/2}.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2000-349746 |
Nov 2000 |
JP |
|
2001-302591 |
Sep 2001 |
JP |
|
Parent Case Info
This application is a continuation patent application of International Application PCT/JP01/09971) filed Nov. 15, 2001.
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Number |
Name |
Date |
Kind |
5540753 |
Takano et al. |
Jul 1996 |
A |
6284016 |
Kitamura et al. |
Sep 2001 |
B1 |
Foreign Referenced Citations (3)
Number |
Date |
Country |
6-228624 |
Aug 1994 |
JP |
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10-20110 |
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JP |
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/JP01/09971 |
Nov 2001 |
US |
Child |
10/183753 |
|
US |