Submerged nozzle brick plays an important role in the continuous casting system of iron and steel industry. Its design characteristics and structural optimization are mainly reflected in the following aspects:

I. Thickening design of slag line

The slag line of traditional submerged nozzle brick is easy to be thinned or even broken due to erosion, thus affecting its service life. The improved submerged nozzle brick has a protective layer at the slag line with a thickness of 10-30mm and a height of 100-250mm, which significantly improves the corrosion resistance and service life.

II. Special runner design

In order to meet the demand of high casting speed continuous casting, the internal flow channel structure of submerged nozzle brick was optimized. For example, CSP thin slab continuous casting high casting speed submerged nozzle brick adopts the structure of molten steel inflow section, equal diameter circular channel section, shunt channel section and expanded outflow section with bowl-shaped channel. Among them, the expanding outflow section adopts the single-hole design with elliptical cross-section, which is more suitable for the inner cavity shape of funnel-shaped crystallizer, and can effectively control the flow of molten steel and reduce the slag entrapment and the fluctuation of molten steel level in the crystallizer.

III. Application of the fluid separator

A special distributor is arranged in the shunting channel section, which can shunt and decelerate the molten steel, reduce turbulence and erosion, and thus improve the quality of the slab. This design is particularly important in high casting speed continuous casting, which can ensure the smooth flow of molten steel in the mold.

IV. Design of large discharge hole

In order to solve the problem of internal blockage of nozzle, by increasing the size of nozzle outlet (for example, from 60mm×80mm to 70mm×90mm) and adopting carbon-free lining, the blockage ratio is effectively reduced and the continuous casting efficiency is improved.

V. Material optimization

Submerged nozzle bricks are usually made of aluminum-carbon or zirconium materials, which have excellent corrosion resistance and thermal shock resistance, and can effectively prevent secondary oxidation of molten steel and inclusion involvement.

VI. Anti-oxidation coating

Coating anti-oxidation coatings on the inner and outer walls of submerged nozzle brick can further improve its corrosion resistance and service life.

VII. Structural stability

The design of submerged nozzle brick needs to ensure the structural stability at high temperature to prevent deformation or damage caused by thermal expansion or erosion.

VIII. Installation and sealing

The installation accuracy of submerged nozzle brick is very high, so it is necessary to ensure the tightness with tundish nozzle to prevent molten steel leakage and air entry. Usually, fiber pad or cement is used for sealing, and it is pressed by lever system.

IX. Adapting to different steel grades and processes

The design of submerged nozzle brick needs to be optimized according to different steel grades and continuous casting process. For example, for special steel grades such as high manganese steel and stainless steel, it is necessary to choose materials with higher corrosion resistance.

Through the above design features and structural optimization, the submerged nozzle brick can effectively improve the continuous casting efficiency, improve the slab quality, reduce the production cost and reduce the consumption of refractory materials.