Lance for blowing oxygen in steelmaking
A lance ( 1 ) for blowing oxygen onto a bath of molten steel including a tip ( 15 ) provided with first oxygen ejector ( 16 ) and a distributor ( 17 ) provided with second ejector ( 18 ).
1 . A lance for blowing oxygen to a bath of molten steel contained in a converter, the lance defining an upper part and a lower part, the lower part being closer to the bath of molten steel, the lance comprising:
a main tube for supply of a primary flux of oxygen;
a second tube surrounding the main tube to form a first annular gap for the circulation of cooling water within the lance;
a third tube surrounding the second tube to form a second annular gap for supply of a secondary flux of oxygen, the third tube extending only along the upper part of the lance;
a fourth tube having a first part surrounding the third tube along the upper part of the lance and having a second part surrounding the second tube along the lower part of the lance, to form a third annular gap for circulation of cooling water within the lance;
a tip, located at an end of the lower part of the lance, provided with at least one primary oxygen ejector for blowing the primary flux of oxygen to the bath of molten steel and being designed to be in fluid connection with both the first and third annular gaps to ensure circulation of water within the lance;
a distributor forming a junction between the upper and the lower part of the lance, the distributor having at least one secondary oxygen ejector in fluid connection with the second annular gap for blowing the secondary flux of oxygen, the at least one secondary oxygen ejector of the distributor being located at distance d above the at least one primary oxygen ejector of the tip so that a ratio between the distance d and an adjacent internal diameter D of the converter is from 0.04 to 0.15.
2 . The lance as recited in claim 1 wherein the ratio is from 0.08 to 0.15.
3 . The lance as recited in claim 1 wherein the at least one secondary oxygen ejector is located from 150 to 750 mm above the at least one primary ejector.
4 . The lance as recited in claim 1 wherein the distributor has a seal preventing leakage of water.
5 . The lance as recited in claim 1 wherein the distributor is mounted slidably around the fourth tube.
6 . The lance as recited in claim 1 wherein the at least one primary ejector includes at least four primary oxygen ejectors.
7 . The lance as recited in claim 1 wherein the at least one primary ejector has an exit diameter from 40 to 50 mm.
8 . The lance as recited in claim 7 wherein the at least one primary oxygen ejector has an exit diameter from 40 to 45 mm.
9 . The lance as recited in claim 1 wherein the at least one primary oxygen ejector is designed so as to eject the primary flux of oxygen with an ejection angle with respect to a central axis of the lance from 10 to 20°.
10 . The lance as recited in claim 1 wherein the at least one primary oxygen ejector is designed so as to eject the primary flux of oxygen with an ejection angle with respect to a central axis of the lance from 14 to 18°.
11 . The lance as recited in claim 1 wherein the at least one secondary oxygen ejector has an exit with an oblong shape.
12 . The lance as recited in claim 1 wherein a biggest dimension of an exit of the at least one secondary oxygen ejector is from 10 to 25 mm.
13 . The lance as recited in claim 1 wherein the first annular gap allows entry of water into the lance and the third annular gap allows exit of water from the lance.