Study On The Long-Campaign Technology Of Baosteel No.3BF

To prolong the campaign life of blast furnace can not only directly reduce the expensive cost of overhaul, but also avoid the huge economic losses caused by stopping production. The vast blast furnace ironmaking workers have focused on the subject of prolonging the campaign life of blast furnace.Blast furnace longevity is a systematic comprehensive project with a lot of influencing factors, and the blast furnace campaign life depends on the combined effect of these factors.In this paper, for No.3blast furnace longevity of Baosteel, systematic research has been conducted from design and manufacture, construction masonry, operation management to testing and maintenance, and No.3blast furnace longevity comprehensive technology with new characteristics has been formed.On the basis of research and analysis of the design deficiency of No.1,2blast furnace, and also absorption of the blast furnace longevity experiences all over the world, Baosteel No.3blast furnace profile design, refractory material configuration, cooling equipment selection and detection monitoring set was researched and optimized carefully, and some new longevity technologies were also adopted, which laid the foundation of No.3blast furnace status stability and longevity. At the beginning of furnace profile design, the combination of design furnace profile and operating furnace profile was carried on the earnest research, fully considering the rationality of actual operating furnace profile after production. Especially the ratio of working height to belly diameter (Hu/D), dead iron layer depth, bosh angle and shaft angle was optimized. Smooth transition from the middle thick stack lining to the upper thin stack lining was ingeniously handled, which was helpful for gas flow distribution control. No.3blast furnace cooling system adopted the whole cast iron cooling staves form and pure water closed circulation cooling. According to the different parts of the furnace body working environment and process requirements, different structure types of cooling staves and firebrick lining was allocated. Especially in the hearth H1-H4sections, new high cooling strength horizontal type cooling staves were adopted, and UCAR high thermal conductivity small pieces of carbon bricks from America were configured, which was essential for No.3blast furnace to maintain a good state in the hearth for a long term.Since put into production, Baosteel No.3blast furnace has realized the rational gas flow distribution through strengthening the raw materials quality management, strictly controlling of alkali and zinc load into the furnace, optimizing the structure of charging, and according to the different period of production conditions, combined with the characteristics and difficulties of blast furnace, carrying on continuous research and optimization of charging system in the upper part and blast system in the lower part, and controlling the appropriate blast kinetic energy and heat load of blast furnace body, thereby ensuring long term stable operation of No.3blast furnace, and achieving world top-ranking technical and economic indexes and longevity achievements.According to the reason analysis of the cooling stave pipe’s relatively early failure after No.3BF was put into production, a series of optimization measures have been taken for the cooling system, which has greatly improved the cooling intensity and water quality, and effectively alleviated the breakage of cooling water pipes. And a number of longevity maintenance measures have been carried out, such as installing micro coolers, pressing stereoplasm, building artificial wall, replacing the whole cooling staves in S3, S4sections and so on, which has significantly improved the longevity situation of furnace shaft, ensured keeping regular operating furnace profile of No.3BF in the late campaign, and created conditions for strengthening smelting.After production for a long time, the hearth of No.3blast furnace has always been in a good condition, not troubled by temperature rise of hearth sidewall like No.K2blast furnace. While with the longer furnace service time, especially still keeping long time high smelting strength when passed the designed furnace life, the temperature of hearth sidewall presents a gradually rising trend. By research and use of many hearth longevity maintenance measures like further improving the hearth cooling strength, strengthening the taphole state maintenance, improving the hearth working activity, strengthening the condition monitoring of hearth, hearth grouting and so on, and No.3blast furnace sidewall temperature can be safely controlled generally with high strengthening smelting in its later campaign. So the campaign life of No.3blast furnace can be prolonged effectively.Through the research and use of the longevity technologies, by October2012, Baosteel No.3blast furnace has been running smoothly and stably for more than18years, the total amount of iron production reached65.41million tons, and the iron production per unit furnace volume is up to15036t/m3. It is still working now, and has created the domestic longevity record of blast furnace.