DEEP PNEUMATIC LIME INJECTION WITH HI_JET TECHNOLOGY AT TENARIS DALMINE
Tenaris is the leading global manufacturer and supplier of tubular products and services used in the drilling, completion and production of oil and gas; in process and power plants; and in specialized industrial and automotive applications with 21,500 employees world-wide and a total annual capacity of 6.000.000 tons. On March 2009, at Tenaris Dalmine located in Dalmine (Italy), the HI_JET injector was installed to pneumatically inject lime in steel interface to improve the phosphorous removal capability.
Tenaris is the leading global manufacturer and supplier of tubular products and services used in the drilling, completion and production of oil and gas; in process and power plants; and in specialized industrial and automotive applications with 21,500 employees world-wide and a total annual capacity of 6.000.000 tons.
Tenaris Dalmine is the steel pipe operations of Tenaris in Italy and is the top Italian producer of seamless steel tubes for the energy, automotive and mechanical industries with outside diameters from 11/16 inch (17.2 mm) to 28 inch (711 mm), in carbon and alloy steel grades. The meltshop has an annual production capacity of 950,000 tons of finished products.
In March 2008, Tenaris Dalmine installed the pneumatic lime/dolo-lime injection system supplied by MORE in their 100 ton electric arc furnace. The supply included two dedicated MOLI dispensers installed under two 125 m3 (4,400 ft3) storage silos. From each MOLI exit, the material was pneumatically conveyed to two LIMEJET combined burner/lime injectors.
After several campaigns, while the customer was trying different layout configurations as well as different kinds of injected materials, the final configuration was reached with one of the two LIMEJET being replaced by a HI_JET injector.
The peculiarity of the HI_JET patented tool is the injection of the fluxes fines embedded into an annular supersonic oxygen stream. Due to the high velocity oxygen stream, the lime particles exchange momentum with the oxygen and increase their speed up to 400 m/s (895 mph), about ten times higher than the exit speed of the traditional lime injectors. Moreover, the HI_JET injector includes the innovative MSF-Mixed Swirl Flame technology (up to 5 MW) for heating and assisted melting of scrap after each scrap bucket charge.
The high speed lime pierces through the slag reaching the steel and consequently improving the interaction with it and minimizing loss in the fumes. The ability to inject lime in steel at the proper temperature range (at the beginning of the refining phase) improved the phosphorous removal capability.
Consolidated results have demonstrated the ability to maintain the same phosphorous content in the steel at tapping by reducing the total amount of lime by 300 kg (661 lb) per heat with a saving of 3 kg/ton (60 lb/ston).
With the ability of the HI_JET to inject the material into the liquid steel, TENARIS DALMINE has decided to install an additional MOLI dispenser to feed the HI_JET injector with alternative slag formers. The third MOLI dispenser is scheduled to be installed in January 2010.
At present, MORE has a scorecard of 35 lime/dololime pneumatic transportation/injection systems worldwide in operation or under manufacturing.