Product Description

A refractory material with a chromium oxide content of more than 30% made from chromium ore. In order to improve the high temperature performance of bricks, more than 10% magnesia is generally added to the material. Chrome bricks are neutral bricks, which are weak against acid and alkaline refractories at high temperatures, and their softening temperature under load and thermal shock resistance are lower than those of magnesia-chrome bricks. It is mainly used for the isolation layer of acidic and basic refractory materials at high temperature, and is also used for the lining of non-ferrous smelting furnaces, but it is not suitable for places where it is in direct contact with molten iron and the atmosphere changes frequently.

Chrome oxide bricks (hereinafter referred to as chrome bricks) were first used in non-ferrous metallurgical furnaces and coal gas slag furnaces. In the past 10 years, this refractory material has been used in glass melting furnaces, but it is only limited to dark bottle glass melting furnaces or alkali-free glass fiber melting furnaces, and is mainly used in high temperature parts of glass melting furnaces, such as the upper pool. Wall, small furnace mouth, liquid flow hole, feeding port, etc.

Characteristic of Chrome brick

As the consumption layer of high temperature resistance, erosion resistance and erosion resistance, high purity chromium oxide material is generally selected, commonly called chromium-aluminum-zirconium brick or high chromium brick. It is required that this part of refractory material has excellent high temperature resistance, high creep resistance strength, thermal shock stability and high temperature chemical stability.In the process of use, the main damage factors of high chromium brick for gasifier are as follows:

(1) chemical erosion

The high chromium brick is mainly eroded by slag, followed by the strong reducing gas in the furnace.In addition, SiO2 and CaO in the slag strongly permeate into the brick and react with the refractory components to form a thicker metamorphic layer.The erosion of high chromium brick by CO, H2 strong reducing gas is mainly caused by the gas and impurities in the brick, such as SiO2, iron-containing oxides reaction to generate gas overflow or under the action of iron oxides reaction with CO to generate C deposition in the brick, resulting in high chromium brick bulging and cracking.

(2) mechanical wear

Mechanical wear is mainly caused by scouring of high chromium brick used in gasifier by high speed gas and carrying slag.The consequence of this scouring is that on the one hand, the chemical reaction between slag and high chromium brick is accelerated, on the other hand, the reaction products of low melting point will be taken away from the brick surface, and on the other hand, the process of spalling of the metamorphic layer and crack site of brick is accelerated.

(3) Operating conditions

The operation technology of gasifier is also the key factor that causes the damage of high chromium brick.

B) Type of coal: the ash melting point of coal determines the operation temperature of gasifier.If the melting point of raw coal ash is too low, the viscosity of coal ash is very small under production conditions, which will aggravate the erosion and penetration of molten slag to hot-faced brick.The coal with high ash melting point often introduces certain additives, such as CaO and Fe2O3, to reduce its melting flow temperature to the best value when preparing CWS. 

C) Production load and times of start and stop: according to statistics, the service life of hot brick decreases by 33% for each increase of production load by 30%;Usually every time the furnace is started and stopped, the corrosion loss of hot face brick is 5-20mm, especially when the CaO content in slag is high.

D) Burner: the experimental study and the actual field operation show that the normal injection Angle of the burner should be about 35°, if the Angle is too large, it will cause serious scour and spalling in the upper part;If the injection Angle is too small, it can not be completely gasified, resulting in lower gasification efficiency.If the burner is offset, the local erosion of furnace lining will be aggravated.

 

Application of Chrome brick

High chrome bricks are mainly suitable for working linings of industrial furnaces with reducing atmosphere such as coal-water slurry pressurized gasifiers.