What is the Performance and Service Life of High Chrome Bricks?

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Performance and application range of high chrome brick

High chromium bricks are made of industrial-grade chromium oxide and alumina as the main raw materials or introduce a small amount of zirconia. After high-temperature firing, a shaped refractory product with a chromium trioxide content of not less than 75% and a combined content of chromium trioxide, alumina, and zirconia not less than 98% is obtained. It has excellent corrosion resistance, high compressive strength at room temperature, high strength at high temperature, excellent wear resistance, high refractoriness, excellent thermal shock resistance, and good volume stability at high temperatures.

High Chrome Bricks

High chromium bricks are divided into four grades according to the content of chromium trioxide: GGZ-75, GGZ-85, GGZ-90, GGZ-95. In the grades, G, G, Z- are the initials of the Chinese phonetic alphabet of Gao, chromium, and brick respectively, and the Arabic numerals are the mass fractions of chromium trioxide.

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

The influence of operating temperature on the service life of high chrome brick

The operating temperature has a great influence on the service life of high chrome bricks(https://www.hy-refractory.com/products/bricks/high-chrome-bricks.html). The higher the temperature, the greater the rate of damage and the lower the service life of the brick. In the working environment of the coal-water slurry gasifier, the essential reason for the high temperature to reduce or significantly reduce the service life of high chrome bricks is that the high-temperature changes or significantly changes the viscosity-temperature characteristics of the cinder. The higher the temperature, the lower the viscosity, the better the fluidity, the more serious the erosion and penetration of bricks, the greater the erosion rate, and the lower the life span. After long-term research and statistical use, the corrosion rate of high chromium bricks will increase by 4 times for every increase of 100°C above the appropriate operating temperature. Or every increase of 44℃, the erosion rate of bricks doubles.

The operating temperature is related to the ash melting point and viscosity of the cinder, and the ash melting point and viscosity of the cinder are directly related to the composition of the cinder, that is, the coal quality of the raw coal. Research and practice at home and abroad believe that the appropriate operating temperature should be about 50°C higher than the melting point of cinder ash or 20-50°C higher than the melting temperature when the slag has good viscosity. The ash melting point of coal slag should be lower than 1300℃, and it is better to control it at 1250-1300℃. The viscosity should also be controlled within the appropriate range of 15~25Pa·s, which can not only ensure that the slag forms an effective protective layer on the working surface, but also maintain a certain fluidity without blocking the slag discharge port. The viscosity should be controlled within 25~35Pa·s at a suitable operating temperature.

The corrosion resistance of high chrome bricks against the cinder

  • (1) The slag resistance of high chrome bricks. Coal melting is an acidic slag with a low melting point and is very corrosive to refractory materials. Both theory and practice show that high chromium bricks are refractory materials with good resistance to cinder erosion.
  • (2) With the increase of temperature, the viscosity of coal slag greatly decreases.
  • (3) The large solubility of various refractory oxides in coal slag is lower than that of chromium oxide.
  • (4) Erosion rate of the furnace lining. With the increase of chromium oxide content, the corrosion rate of furnace lining decreases. The relationship between lining erosion rate and chromium oxide content.
  • (5) The anti-slag erosion rate of high chromium bricks with chromium oxide content of 60% ~ 90%.

In order to reduce the melting point of coal slag and ensure smooth production, a certain amount of lime (CaO) is added to the coal raw materials for the coal water slurry gasifier. Finally, calcium oxide in the coal slag increases, and the corrosion resistance rate of high chromium bricks accelerates. The erosion rate of coal ash with different CaO content on high chromium bricks is different.

What should I do if the refractory lining material cracks, falls off, and is easy to wear? To completely solve the problem, you need to dig from the root cause and analyze the real cause. Rongsheng Refractories Manufacturer has been engaged in refractory production and R&D services for many years and can solve various difficult problems of the high-temperature furnace lining. Welcome new and old friends for consultation and technical exchanges.

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