The furnace body consists of a furnace wall, a furnace bottom and a furnace roof. The end burner is installed on the end wall on one side of the furnace, the discharge door is installed on the end wall of the soaking section, and the feed door is installed on the end wall on the other side. In addition to the furnace door and manhole, the side burner is sometimes installed on the side wall of the heating section; the bottom of the push-type steel furnace is composed of a soaking bed, a water-cooled tube slide or a ceramic slide brick, and the bottom of the walking furnace is composed of a fixed beam (bottom) and a walking beam. Usually, the furnace bottom refers to the solid furnace bottom made of bricks or amorphous refractory materials. The furnace roof is divided into a dome and a flat top. The furnace roof is affected by factors such as high temperature, airflow scouring, thermal stress, etc., especially the furnace roof at the front of the heating section and the soaking section, which is easily damaged.
1.Brick furnace body
The furnace lining is made of insulation bricks and refractory bricks. The insulation layer of the furnace is made of clay or high-alumina insulation bricks, floating bead bricks, diatomite bricks and refractory fiber felt, with a thickness of 113~2300mm. The working layer of the furnace wall is built with clay refractory bricks, with a thickness of 230mm~400mm. The openings can be made of brick arches, special-shaped bricks or covered with long clay refractory bricks. If the furnace wall is high, high-alumina tensile bricks need to be installed at an appropriate distance to prevent the furnace wall from tipping over. At the same time, the bottom of the furnace wall in the heating section should be thickened to increase its stability. The furnace wall is easily damaged by the collision of the steel billet. The openings around the furnace wall and the side steel outlet are easily damaged by high temperature, rapid cooling, rapid heating and mechanical damage. The working layer thickness of the furnace bottom is 300~400mm. The preheating section is built with clay refractory bricks, and the heating section is built with clay or high-aluminum refractory bricks. A layer of metallurgical magnesia sand is laid on it. In order to resist the erosion of iron oxide slag, a protective layer can also be directly built with magnesia bricks or magnesia-chrome bricks. Due to high temperature and billet impact, mobile wear, slag erosion and other reasons, the solid bottom soaking bed of the soaking section is damaged quickly. When high-aluminum bricks or magnesia bricks are used as the working layer in this part, the service life is about half a year, and the service life of fused mullite bricks or corundum bricks can be extended to about one year. When the furnace roof is a brick vault, the working layer thickness is 230~1200 mm thickened, and the insulation layer is 300 mm~300 mm thickened. When using a suspended ceiling, the working layer thickness is 230~The insulation layer thickness is about 70mm, 250mm. The hanging bricks used to suspend the flat roof are divided into single groove type, single-sided groove type, double-sided groove type and clamping type. Generally, soil-turning hanging bricks are used, and high-aluminum hanging bricks are also used in high-temperature areas. The special-shaped hanging bricks commonly used in the lower part of the furnace top pressure do not need to be used as an insulation layer. The service life of the clay refractory brick roof is 1~2 years, and the service life of the high-aluminum brick furnace top is slightly higher. After changing the fired bricks to unfired high-aluminum hanging bricks, the service life can be increased by about 1 times. The service life of the rolling steel heating furnace is generally 1~3 years under normal operating conditions, and the service life of the forging steel heating furnace is 3~11 months due to intermittent operation, thermal stress and mechanical collision.
2.Prefabricated block hoisting furnace body
Precast blocks are made of refractory castable materials such as aluminate cement, phosphate low cement and water glass. If the precast blocks are made of clay and refractory castable materials, they need to be equipped with anchor bricks. The furnace roof precast blocks are divided into arched and long strips. If equipped with steel bars, they are placed in the non-working layer.
3.Furnace body made of refractory plastic
The working layer of the furnace lining with anchors is made of refractory plastic. The gaps between the anchor bricks or hanging bricks should be filled with refractory plastic blanks and crushed with a pneumatic hammer or a tamping machine. The refractory plastic, including the furnace bottom, is generally constructed in layers and sections continuously, with the surface scraped, the exhaust holes tied tight, and the expansion joints cut. The refractory plastic furnace lining has the advantages of strong integrity, good sintering, and high high temperature strength. Therefore, the furnace lining generally does not peel off and has a service life of about 13 years.
4.Casting the furnace body with lining castable
The working layer of the furnace lining is cast on site with refractory castables. The structure of the furnace wall and the furnace roof is the same as that of the refractory plastic furnace. After the anchor bricks or hanging bricks are installed in place, the refractory castable mixture is arranged from one side, and then vibrated and compacted with a vibrator (handheld), and continuous construction and timely maintenance should be carried out. Before 1980, the working layer of the furnace lining was generally cast with high-aluminum cement or phosphate refractory castables, but the working layer of the furnace lining in the high-temperature area is prone to structural peeling, affecting the use. The service life is generally 2 to 4 years. After 1980, the furnace body generally uses various clay combinations or low-cement series refractory castables to cast the working layer of the furnace lining. Sometimes, the furnace bottom in the high-temperature zone is cast with wear-resistant and heat-resistant steel fiber refractory castables and slag-resistant corundum, mullite or magnesia-chromium refractory castables. The baking time is about 8 days. Under normal operating conditions, the service life of the rolling steel heating furnace can reach 4 days~10 years for the forging steel heating furnace, and the service life is 2 to 4 years.
Burner brick is a refractory product used in various burner parts, which mainly plays the role of gathering flames. Flame burners are installed on the furnace roof, and other burners are installed on the furnace wall. The burner brick is trumpet-shaped, composed of one or several pieces, and is embedded in the furnace lining. The center is aligned with the center of the burner to ensure effective mixing and preheating of fuel and air, organize the flame shape, and stabilize the combustion process. The brick and the lining around it are often affected by high temperature, sudden temperature changes, and airflow scouring. Damage is very fast. The service life of clay burner bricks for gas is about 1 year. When heavy oil is used as fuel, its service life is only 3 years to 6 months. When high-aluminum or silica burner bricks are used, the use effect is improved; the service life of burner bricks made of high-aluminum cement or phosphate refractory castables for gas heating furnaces is 1 to 2 years. The burner bricks made of corundum or mullite low-cement series refractory castables for oil heating furnaces have a service life of 6 months to 3 years.
