LD-CONVERTER’s OXYGEN LANCE REPAIR SECTION.
(Steelmaking
Department Pakistan Steel )
The optimal design of oxygen blowing lance and lance head with effective passage of cooling water and certain axes of orifice /nozzles as per explicit internal dimensions of LD-Converter is acquired to manage the desired quality of steel production, faster and smooth process and to prevent the excessive wearing of refractory lining of LD-Converter from attack of vigorous slag forming reactions.
The water cooled oxygen blowing lance for LD-Converter (steel making) is comprised of a rear body from which the lance hangs and an orifice tip connected by three concentric seamless pipes or tube sections joined by welding to form a straight continuous member of ample length. In a typical design the oxygen flows through the center pipe which is surrounded by inlet water moving down through the adjacent annular passage to the orifice tip, the water returns through the the outer annular passage to the rear body and discharge connection. The intermediate pipe serves as a baffle separating the inlet and discharge water as it flows through the lance with suitable clearance at either end to minimize the amount of bypassing water.
The water cooled oxygen blowing lance for LD-Converter (steel making) is comprised of a rear body from which the lance hangs and an orifice tip connected by three concentric seamless pipes or tube sections joined by welding to form a straight continuous member of ample length. In a typical design the oxygen flows through the center pipe which is surrounded by inlet water moving down through the adjacent annular passage to the orifice tip, the water returns through the the outer annular passage to the rear body and discharge connection. The intermediate pipe serves as a baffle separating the inlet and discharge water as it flows through the lance with suitable clearance at either end to minimize the amount of bypassing water.
The lance life is defined as the total number
of heats blown by it between replacements of the orifice tip or front end
sub-assembly. Lance repairs and frequency of lance changes are a matter of
concern due to the labour involved and hence related effect on cost per ton of
steel produced.
Lance repairs include skull removal, as well
as replacement of the orifice tip or other sections that may be leaking or
otherwise defective, restoring the three concentric pipes to full design
length, attaching rear body, filling with water and lastly pressure testing to
specified limits.
Most lance failures are due to water leaks
which develop in or adjacent to the orifice tip, mostly as a result of erosion
by molten metal and slag moving down and across the exposed lance surface
during process of steelmaking. Survival of the lance under the furnace vigorous
high temperature conditions depends completely on the effectiveness of the
cooling water in removing the heat absorbed on the exposed surface and proper
lance height during course of oxygen blowing.
Appearance of Oxygen Lance Head.
The water cooled Oxygen blowing lance copper
head has a set of tapered nozzles with precise dimensions designed according to
specific volume of LD-Converter and blowing practice. Slight alteration in
dimensions directly affects the quality, production performance and refractory
lining campaign of LD-Converter.
Pakistan
steel handles lance repairs at “ in house” available facilities in steelmaking
department, uses lance heads with five orifice /nozzles for 130 ton
LD-Converter steelmaking and is self-sufficient in provision of these important
spares.