The Oita No. 1 Blast Furnace (currently in its second campaigne) was blown in August 1979 and commenced so called "all coke operation" in March 1980. Further Nippon Steel induced the Pulverized Coal Injection (PCI) technology from ARMCO which uses coal as an auxiliary fuel in place of oil. This technology has been in practice on a commercial basis for many years at ARMCO. On June 26, 1981, Oita was successful in adapting this PCI technology to a large blast furnace of 4000 m3 inner volume involving a super high top pressure with a high blast temperature. Both the equipment and the operation have made good progress up to date.
In this report, the mechanical out line and major characteristics of the PCI system have been presented as well as developments of technologies for adaption to a large furnace, especially in respect to the combustion and raceway characteristics and control for stabilized transport as affected by scaling up under a high pressure and a high blast temperature conditions. Furthermore, the details of full scale tests are described, which were conducted by utilizing a single-tuyere test facility which was installed on the Oita No. 2 BF. Operational results have shown a satisfactory distribution uniformity throughout tuyere lines around the furnace.
As far start-up operation, the aimed injection levels, projected step up rates of injection and optimization of operational conditions are reported herein together with actual operational performance such as the replacement ratio of PC to coke, stability of hot metal quality, material and heat balance and circumferential balance.