High chrome bricks are mainly made of industrial-grade chromium trioxide and alumina, or a small amount of zirconia is introduced. It is a shaped refractory product obtained by high-temperature firing, the content of chromium trioxide is not less than 75%, and the content of chromium trioxide, alumina, and zirconia is not less than 98%. High chromium brick industrial furnace lining resistant to cinder erosion, which has excellent corrosion resistance, high compressive strength at room temperature, and high-temperature strength. Excellent wear resistance, high refractoriness, excellent thermal shock resistance, good volume stability at high temperatures, etc.
High chromium bricks are mainly suitable for the working lining of coal-water slurry pressurized gasification furnaces and other related reducing atmosphere industrial furnaces. High chromium bricks are divided into four grades according to the content of chromium trioxide: GGZ-75, GGZ-85, GGZ-90, and GGZ-95.
The operating temperature has a great influence on the service life of high chrome bricks. The higher the temperature, the greater the erosion rate and the lower the service life of the brick. In the working environment of the coal-water slurry gasifier, the essential reason for reducing or significantly reducing the service life of high-chrome bricks due to high temperature is that high-temperature changes or significantly changes the viscosity-temperature characteristics of cinder. The higher the temperature, the lower the viscosity, the better the fluidity, and the more serious the erosion and penetration of bricks. The greater the erosion rate, the lower the lifetime. After long-term research and use statistics, above the appropriate operating temperature, the erosion rate of high chrome bricks will increase by 4 times for every increase of 100 ℃ or double the erosion rate of bricks for every increase of 44 ℃.
Why Can High Chrome Bricks be Used in the Working Lining of Coal-Water Slurry Gasifiers?
(1) Slag resistance of high chrome bricks. Coal slag is an acidic slag with a low melting point and is very corrosive to refractory materials. Both theory and practice show that high chromium brick is a refractory material with good resistance to cinder erosion.
(2) The viscosity of coal slag decreases significantly with the increase in temperature.
(3) The solubility of various refractory oxides in cinder is lower than that of chromium oxide.
(4) Lining erosion rate. With the increase of chromium oxide content in high chrome bricks, the erosion rate of furnace lining decreases accordingly. The corrosion rate of furnace lining as a function of chromium oxide content.
(5) The slag erosion resistance rate of high chromium bricks (Zirchrom) with a chromium oxide content of 60% to 90%.
In order to lower the melting point of coal slag and ensure smooth production, a certain amount of lime (CaO) is added to the coal raw material for the coal-water slurry gasifier. Therefore, calcium oxide increases in coal slag, and the corrosion resistance rate of high chrome bricks is accelerated. Coals with different CaO contents have different erosion rates than high chrome bricks.
Chromium bricks are neutral bricks, which have weak effects on acidic and alkaline refractory materials at high temperatures. Its load-softening temperature and thermal shock resistance are lower than that of magnesia-chrome bricks. It is mainly used as the isolation layer of acidic and alkaline refractory materials under high temperatures. It 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.
Like all refractory bricks, the phase composition, specific properties of any type of high chrome bricks, and how to essentially change some specific properties of the material depend first on its chemical composition. The chemical composition, especially the chromium oxide content, plays a decisive role in the high-temperature properties and corrosion resistance of refractory materials. High chrome bricks are based on the chemical composition of chromium oxide. Determining the chemical composition also determines the grade and basic performance of the product. Users can choose the corresponding brand according to the different requirements of use, so as to achieve the best use effect. At the same time, chromium oxide resources can be fully utilized.
What should I do if the refractory material cracks, falls off, and is easy to wear? If you want to solve the problem, you need to dig out from the root and analyze the real reason. Rongsheng refractory brick manufacturer has been engaged in refractory material production and research and development services for many years and can solve various difficult problems in the lining of high-temperature kilns. Any requirements, please contact us. We not only provide free price information, but also free samples, and customized industrial furnace lining solutions.
