The effect of reducing gas injection on the coke rate and coke to oil replacementratio was investigated in an experimental furnace of 3.2 m3 inner volume under conditions similar to a commercial furnace. Reducing gas made by partial combustion of oil with oxygen was injected at a constant blast volume.
(1) The 571 kg/t HM of coke rate in the standard process decreased to 374 kg/tHM with 628 Nm3/tHM of gas injection. The replacement ratio was between 0.75 and 0.82 depending on the amount of injected gas.
(2) An appropriate amount of injection of reducing gas together with oxygen enrichment improved heat exchange condition at the furnace shaft to increase productivity without any increase in coke rate.
(3) 85 percent of oxygen of are was removed by CO and H2 with 628Nm3/tHM of injected gas in comparison with 65% in the standard process. Ore reduced in the same retention time increased by two times by this gas injection.
(4) By considering the staged heat balance, it was shown that the gas should contain less CO2 and H2O and had to be heated above 1000°C. The gas should be injected at below the thermal reserve zone.
(5) The economy of the technipue depended on the prices of coke and gas, and the replacement ratio. Even at present, this technipue has been proved to be economical.
