The so-called top-fired hot blast stove
means that the burner is installed on the top of the hot blast stove of ironmaking equipment and burns in the vault space without the need for a special combustion chamber, also known as Combustion chamberless hot air stove.
To introduce gas directly into the vault space for combustion, in order to ensure good mixing and complete combustion of gas and air in a short period of time, it is necessary to use a short flame or flameless combustion burner with large combustion capacity. Commonly used are semi-jet short flame burners.
Due to the high hot air outlet of the top-fired hot blast stove, the installation plane of the hot blast main pipe is high, which requires high strength of the pillar structure. Therefore, the hot blast stove is arranged in a rectangular combination. Top-fired hot blast stoves require mechanization and automation for operation, maintenance, and installation because the burner, hot blast valve, etc. are all located on the stove top platform.
In addition, because these water-cooled valves are installed at a very high altitude, the water supply pressure of the cooling water must also be increased accordingly. The key to the use of large top-fired hot blast stoves lies in high-power and efficient short-flame burners. design. The top-fired hot blast stove absorbs the advantages of internal combustion and external combustion hot blast stoves and overcomes some of their shortcomings.
Its structure can adapt to the requirements of modern blast furnaces developing towards high temperature, high pressure and large size.< /p>
The combustion capacity successfully reduces a lot of equipment while meeting production requirements,
facilitating production operation and management. Therefore, it represents the development direction of a new generation of high blast temperature hot blast stoves.
In a hot blast furnace, the high-temperature flame and combustion products generated by fuel combustion directly wash away the furnace walls and the refractory masonry of the vault. The dust in the gas reacts chemically with the refractory materials, and the grid bricks and furnace walls are affected by the chemical reaction. Deformation due to long-term loading will cause damage to the masonry.
Masonry is subject to high temperature, with high inner surface temperature and low outer surface temperature.
The internal expansion is large and the external expansion is small. Therefore, the internal surface of the masonry is subject to compressive stress and the external surface is subject to tensile stress. . The inner surface of the brick is easily damaged locally,
which causes thermal spalling on the brick surface and cracking of the brick joints, causing the brick arch or vault brickwork to sink. Dust in the products of combustion reacts chemically with the bricks, forming low-melting compounds that melt at high temperatures, which is another cause of spalling of vault brickwork. On large hot blast stoves, this peeling phenomenon is more serious, especially when the temperature is too high due to improper operation, the thermal peeling is more serious.
On the lower horizontal plane of grid bricks or furnace wall masonry,
The masonry is subject to a large self-compression load, coupled with the effect of repeated fluctuations in temperature, the masonry is prone to collapse. Cracks and deformation occur.
The highest surface temperature of refractory bricks is used as the working temperature for hot blast stove masonry, and this is used as the standard for selecting refractory bricks. The high-temperature parts of the hot blast stove, including the vault, the upper part of the combustion chamber, the upper grating bricks of the regenerator and the furnace wall, take the vault temperature as the operating temperature. Therefore, the refractory resistance and creep properties of the refractory materials should be higher than those of the vault. top temperature. Silica bricks or high-quality high-alumina bricks are often used in these parts. Excerpted from: Metallurgical Industry