The COJET® Gas Injection system uses a process and injector nozzle that delivers a 3 to 5 foot laser-like coherent jet of oxygen at supersonic speeds into the molten bath in an electric arc furnace. The fixed, wall-mounted injector nozzle retains the original diameter and velocity of the oxygen jet, delivering precise amounts of oxygen to the steel bath with less cavity formation and splash compared to traditional manipulators. Once the oxygen jet impinges on the steel bath, the concentrated momentum of the oxygen beam dissipates in the steel as fine bubbles, providing deep penetration and effective slag-metal mixing. The nozzle also operates as a conventional sidewall burner to melt scrap and as a supplemental oxygen source for post-combustion, improving furnace productivity and decreasing power consumption.
In addition, the technology allows for automatic furnace operation, decreases metal production costs through lower power consumption, extended furnace life and decreased maintenance, and decreases refractory erosion, arc flare damage and maintenance gunning. It also enhances slag foaming, speeds decarburization, eliminates the need for lance manipulators, decreases splashing, and improves slag-metal stirring.
To decarbonize the chemical energy input into EAFs, Linde has developed COJET injectors with hydrogen fuel with excellent results. Hydrogen extends the coherent jet length to 85 nozzle diameters, increases heat transfer, and reduces plugging/maintenance of the injectors. These features make hydrogen an ideal fuel for the COJET system and pave the way to fully decarbonize the EAF.
- COJET technology has been developed to operate with NG, LPG, COG, Fuel Oil, and H2
- Relative to all other fuels, H2 is the ideal fuel; it can produce the longest jets
- Oxygen-Hydrogen for scrap heating and melting: burners can be operated at high velocity, even supersonic – which increases heat transfer and reduces plugging/maintenance of the injectors
- Existing COJET injectors can be used with H2 fuel