輪西町第3高爐操業の特異性について

抄録

The Wanishi-machi No. 3 Blast Furnace (Nominal capaeity 225t/day, hearth diameter 4.3m, inner volume 356m³) is the smallest of the kind now operating in Japan. But the blower used for this furnace has a large capacity enough for 500t/day operation. Therefore several counter- measures to the furnace operation were taken according to the change of conditions during the period since its blow-in of June 1948, and we have got various interesting results.
1. Common Blast Operation.
During the long period of a year and four months from June 1, 1948 to September 12, 1949, common blast operation with the same blower was smoothly kept on together with Wanishi-machi No. 4 Blast Furnace (Nominal capacity 225t/day then also in operation.
2. Operation with the Use of Low Grade Coke.
Since shut-down of No. 4 Blast Furnace in September 1949, the single operating furnace has been obliged to use the coke made only from Hokkaido coal and without blending of coalite. The drum index of that coke was as low as about 55%. Besides, for the purpose of raising the yield of lump coke, nut size coke was used to mix some 20%.
In order to maintain the best output of pig iron under such unfavourable conditions, the following counter-measures were successively applied all of which proved good results.
a) A heavy charge operation by increasing the ore/coke ratio up to 1.85, and the coke ratio could be lowered to 0.85. (Period of Practice: Sept. 1949Feb. 1950)
b) Rise of the blast pressure from 700-800g/cm² to 900g/cm², so that the operation might be kept on in good condition. (Period of practice: March 1950-July 1950)
c) Enlargement of the diameter of tuyeres from 110mm to 130mm, so that the blast volume might be increased to bring more output of pig iron. (Period of practice: August 1950-up to date)