Introduction

Blast furnace hot blast stove is a kind of regenerative exchanger, that is, it can blast into the blast furnace combustion-supporting air from room temperature to high temperature thermal equipment.

The working air temperature of the blast furnace in the 1950s was generally about 800 C, exceeded 1020 C in the 1970s and reached 1350 C in the 1990s. As the air temperature increases, the operating conditions are more harsh, so the refractories used are also from ordinary materials to high performance, variety direction, to meet the needs of high air temperature operation.

In addition to considering volume density and specific heat capacity related to heat capacity, the anti-rubbing property of refractories for hot blast stoves is still the most important index. Thermal shock resistance and strength, accurate shape and no residual expansion are all important properties. Nowadays, purified blast furnace gas is used, so the collapse or blockage of lattice brick caused by expansion cracking (about 1000 C) is not serious.

Refractory for furnace body

The stove body of hot blast stove is composed of regenerator and combustion chamber. The hot blast stove generally uses blast furnace gas or blast furnace and coke oven gas mixture as fuel, but also uses coke oven gas or heavy oil as fuel, its operating temperature is 1300 ~ 1600 C.

Owing to the difference of furnace structure and operation temperature, super or high-grade clay brick, high-alumina brick, silica brick, mullite brick, sillimanite brick, andalusite brick and some amorphous refractories are generally used in various parts.

The damaged parts are mainly the combustion chamber, the upper part of the lattice brick gas, the partition wall of the internal combustion furnace and the bridge of the external combustion chamber furnace.

The damage is mainly caused by high temperature, thermal stress caused by temperature change and chemical erosion of dust. The service life of the hot blast stove is 15~20 years, during which minor repairs to the vulnerable parts are necessary.

Refractories for regenerator

When the temperature of hot air is below 900, high alumina bricks are used for lining bricks and lattice bricks at high temperatures, and high-grade clay bricks are used for the rest; when the temperature of wind is between 900 and 1100, high alumina bricks, mullite bricks or sillimanite bricks are used for lining bricks and lattice bricks at high temperatures, and high alumina bricks and high-grade clay bricks are used for the rest; when the temperature of wind is above 1100 degrees centigrade. The high temperature parts must be made of low Confucian high alumina bricks, mullite and silica bricks.

Refractories for combustion chambers

The refractories used in the combustion chamber are basically the same as those used in the regenerator, and they are also made of mullite or mullite bricks with silica bricks; the air and gas passages of the burner are usually made of clay bricks and high alumina bricks, and the parts with radiation holes (nozzles) on the top of the burner can be made of mullite bricks or mullite corundum bricks, with a service life of 2-4 years. . The parts with nozzles are prefabricated with high alumina refractory castables, and good results are obtained.