HIGH SPEED GAS INJECTION AND ITS DEVICE

摘要

PURPOSE: To protect a nozzle by injecting a protective gas having same composition as a main gas from a nozzle into a cavity at a point set back from the opening while traversing the periphery of the nozzle. CONSTITUTION: A cavity 3 having an opening 4 of diameter D communicates with a combustion zone 2 where a furnace gas 9 is present and main gas 7 is injected into the cavity 3 from a nozzle 6 at a point set back by a length L (L/D<3.0) from the opening 4 at a speed higher than 60 m/sec. A protective gas 11 having substantially same composition as the main gas 7 is injected into the cavity 3 from the nozzle 6 at a point set back farther from the opening 4 at a speed lower than 30 m/sec and at a flow rate 10-50% that of the total gas. The protective gas 11 is fed to the periphery of the nozzle 6 while traversing it and the protective gas 11 is entrained into the flow of the main gas 7 in the downstream of the nozzle 6 thus protecting the nozzle 6.