The blast furnace hot blast stove is a regenerative heat exchanger, which mainly provides a high-temperature heating environment for the combustion-supporting air of the blast furnace to achieve a high operating air temperature, generally 1200-1350 °C. There are three to four hot blast stoves commonly used in blast furnaces. In order to meet the requirements of high temperature heat source and long service time of hot blast stoves, the refractory materials for hot blast stoves should have the characteristics of high temperature resistance, high pressure resistance, good creep resistance, large specific heat capacity, and good thermal conductivity.
There are many types of blast furnace hot blast stoves. According to the structure, they can be divided into internal combustion type, external combustion type and top combustion type. Today, let's take a look at the refractory materials used in various parts of the internal combustion hot blast stove.
The top of the furnace is located in the high temperature area inside the hot blast furnace, where the refractory material directly contacts the hot air and flue gas. The refractory material with strong thermal shock resistance and creep resistance should be selected. Generally, silica brick, low-creep clay brick, High alumina bricks, high alumina thermal insulation bricks, mullite bricks, light clay bricks andalusite bricks, acid-resistant spray coatings, clay spray coatings, etc.
The regenerator is the main place for the heat exchange of the hot blast stove, which is made of checkered bricks of various materials. The upper high temperature zone should use refractory materials with good high temperature volume stability, erosion resistance and creep resistance. Good performance for thermal shock stability.
The upper lattice bricks of the regenerator generally use siliceous lattice bricks and high-alumina lattice bricks.
The middle part uses low-creep high-alumina checker bricks and high-alumina checker bricks.
The lower part uses low-creep high-alumina checker bricks and clay checker bricks.
The large wall of the regenerator is the large wall of the furnace body of the hot blast stove. The temperature in the upper part is high, and the wind temperature in the middle and lower part is relatively low.
Silica bricks, low-creep high-alumina bricks, high-alumina insulation bricks, mullite bricks, light clay bricks, acid-resistant spray paints, light-weight spray paints, etc. can be used on the top of the large wall of the regenerator.
In the middle of the large wall of the regenerator, low creep high alumina bricks, mullite bricks, andalusite bricks, light clay bricks, clay spray paint, light weight spray paint, etc. can be used.
Clay bricks, high-alumina bricks, light-weight clay bricks, high-alumina insulation bricks, clay castables, light-weight spray paints, heat-resistant concrete, etc. can be used in the lower part of the large wall of the regenerator
The partition wall is a refractory material that separates the regenerator from the combustion chamber. The height of the brick wall partition wall is generally 400-700 mm higher than that of the regenerative lattice brick to ensure uniform airflow distribution. Due to the large temperature difference between the two sides of the partition wall, the thermal expansion difference of the wall body becomes larger, which causes the refractory material of the partition wall to deform and bend, and then cracks appear.
Silica bricks and high alumina bricks can be used as refractory materials for the upper part of the partition wall.
High-alumina bricks and high-alumina thermal insulation bricks can be used in the middle of the partition wall.
Low-creep high-alumina bricks and high-alumina thermal insulation bricks can be used for thermal shock parts.
Clay bricks and light clay bricks can be used for the lower part of the partition wall.
The refractory material configuration of the large wall of the combustion chamber and the large wall of the regenerator is basically the same.
Silica bricks, high alumina bricks, high alumina thermal insulation bricks, lightweight silica bricks, lightweight clay bricks, etc. can be used for the upper part.
High-alumina bricks, low-creep high-alumina bricks, high-alumina thermal insulation bricks, and lightweight clay brick spray coatings can be used in the middle.
The lower part can use clay bricks, high alumina bricks, light clay bricks, spray paint, heat-resistant concrete, etc.
It is a device that sends the gas mixed air into the combustion chamber for combustion. There are metal materials and ceramic materials. At present, most of the ceramic burners are used. In order to ensure the air tightness, integrity and service life of the burner nozzle, it is required here. The linear expansion coefficient and creep resistance of refractory materials are good, so the burner nozzle can be made of mullite material, mullite-cordierite material, high alumina-cordierite material, high alumina castable prefabricated parts, etc.
Refractory materials for hot air pipes: including main air supply pipes, branch pipes and hot air surrounding pipes. It is generally made of light clay bricks, and the interface between the hot air outlet and the main air duct can be built with high-alumina bricks and mullite bricks. The surrounding pipes and air supply branch pipes of the hot blast stove can be made by integral casting of high alumina cement refractory castables and phosphate refractory castables.
Refractory material for hot air valve: Therefore, it is heated on both sides, and is affected by mechanical vibration, corrosion and temperature changes. The service life of using clay bricks and high-alumina bricks for masonry is 6~10 months, and the life of high-alumina cement refractory castables is used for casting and forming. Up to 1.5 years or so.
Refractory materials are used in the flue and chimney: the flue and chimney are mainly used for the discharge of smoke and waste, and the flue is longer than the chimney. Brick as a protective layer.
