ON BLAST FURNACE TUYERE

Yoshikazu Nakada.-Every blast furnace man desires to avoid of the beakout from the blast furnace if possible, because it spoils a great deal of furnace conditions and may accompany sometimes dangerous to men. It is a very popular fact that at the tip of an inhaler, owing to a strong flow of steam, there occurs a pretty powerful depression, by which a volume of water in a vessel putdownward, can easily be sucked up. A similar phenomenon may occur, too, at the tuyre end in blast as everyman can easily understand. In the latter case, however, instead of water, some hghly heated molten materials will be drawn up or from the other point of view, they will attack against a tuyre tip, where a depression occurs, and bring this at last to break. The stronger the blast, the more mighty the depression, and an impinging action will become more effective. It is able to say therefore that the blast is a powerful destro ger of tuyres. Naturally almost all pant of blast blown in, flowa directly upward along its upper lip and not any along the lower pant. This upward flow serves to disturb or weeken the depression and to blow about, too molten materials comming to tuyres, but on the contrary not any at the lower. Thus it will be able to explain why breakouts occur mostly, as every man see, at their lower lips. Intending to avoid the paltial upward fllow of the blast and disperse it for all directions, the tuyre end is cut on the bias as shown on a sketch. With the new form the lower. end being shorter, a flow begines earlier from the point "b" and natully this flow takes its way somewhat downward. An inclination "α" has duty to keep always the direction of the tuyre and the flow, too, down ward, even such a case that the tuyre will be thrusted up by growing up of the breast wall very possible by heat.The following comparison tells us how much the improved tuyre gave a good result. "a" blast furnace. Kamaishi. On sep. 26th. 1926 all tuyeres were changed with the new forms and after that the breckout has reduced to onesixth while the production increased to 111.5% having compared with the last four mouths.