The so-called end-bottom structure refers to the structural arrangement between the water pocket at the bottom of the nozzle and the end wall. This involves the shape of the water pocket, the central manhole and the water conduction method at the top and bottom, the thickness of the end and bottom and the water cooling gap, as well as the new structural form that combines extrusion and casting for the purpose of increasing the mass density of the end wall, etc. . The early oxygen lance nozzle used a single hole with a small end and bottom area, and its cooling and structural processing were relatively easy.
However, after the promotion of the use of three-hole guns, certain troubles were encountered in cooling and structural ceramic machining. If the forged head structure is still used, a serious “nosing” phenomenon will occur. If a fine welding structure is used instead, the “nosing” phenomenon will occur. Although the “nose” phenomenon has been solved, the service life is relatively low due to the influence of the end and bottom welds. Later, the center water-cooled casting nozzle that has been widely used in the industry has appeared. Due to the continuous improvement of the casting process and structure, the service life has been greatly improved.
However, the improvement in its service life is still limited by the end and bottom structure of the nozzle and the quality of the water flow organization. For example, a nozzle with a reasonable design structure, appropriate water flow organization, and good production quality can have a service life of 500-600 furnaces. The life of a general nozzle is only 300. There are about 100 furnaces, and the worse ones even have less than 100 furnaces.