Some characteristics mainly concerning to gas-permeability and stock movement of No 1 B. F.(of 350m3 inner volume) at Nishijima Works, Osaka Seiko Co. were investigated and following results were ob-tained.
(1) Periodic changes from tapping to tapping were observed in blast distribution among tuyeres, top gas composition, radial gas distribution, pressure drop, minute pressure pulsation and stock descending. These changes were quite similar to those obtained in small experimental B. F.(of 0.5m3 inner volume).
(2) Under the normal conditions, vertical pressure distribution was nearly linear from tuyere level to stock line. Pressure drop at combustion zone was estimated to be 26-34.8% of total pressure drop between blow-pipe and furnace top. In the case of unusual state, a part of stock column with large pres-sure drop appeared often at upper level of shaft and then it descended downward.
(3) Even under the normal condition, minute pressure pulsation of 0.6-2.13 Hz frequency, which suggested the occurence of “boiling” of solid particles, was observed. When unusual stock movement appeared at the shaft, increase of energy level of low frequency components, which suggested the occurence of “bubbling” or “near-slugging”, was observed. In the case of irregularities at high-temperature region another type of pulsation with 6-18 Hz frequency, which suggested bubbling in liquid phase, were observed before the appearance of pulsation cited above.
(4) It was presumed that unusual stock movement was mainly caused by the occurence of violent fluidization of solid particles even in high temperature region. It seems to be difficult to attribute the irregularities in the melting zone, where nonuniform distribution of fluid flow is remarkable, to the occurrence of “flooding”.
