Gas flow rate vs. pressure in tank for optimum dimension of submerged tuyere in refining furnace

Numerical analysis and experiments on gas flow rate through a submerged tuyere versus pressure in a tank were carried out to design an optimal flow pattern of bottom-brown gas in a refining furnace. The gas flow in the tuyere was formulated as an isentropic flow with friction. When the Mach number reached unity at the tuyere front, the mass flow rate was proportional to the pressure in the tank. The calculated results for compressed gas flow under high pressure in the tank agreed well with those of the experiments. The pressure in the tank increased with the increase in pulverized lime injection rate under the same gas flow rate. Regarding the gas flow pattern at the final refining stage to minimize iron oxide, the gas flow rate is decreased in a bottom-blown converter, whereas the submerged gas flow rate is increased in a top- and bottom-blown converter. A region of allowable gas flow rate and pressure control range was shown where neither drilling of gas jet through the bath nor leakage of steel melt in a tuyere occurs.