The load softening temperature of high chrome bricks is greater than or equal to 1700 degrees, which means that high chrome bricks can be used for a long time in a high temperature environment of 1700 ℃ and below.
Gaoming bricks are made of chromium oxide and aluminum oxide as the main raw materials, or introduced into zirconia, and fired at high temperature to obtain a chromium oxide content of not less than 75%, and a chromium oxide, aluminum oxide and zirconia content of not less than 98%. shaped refractory products. High chrome bricks are generally chrome oxide products produced with industrial pure chrome green as the main raw material. High chrome bricks have the characteristics of excellent corrosion resistance, high compressive strength at room temperature, high temperature strength, excellent wear resistance, high refractoriness, excellent thermal shock resistance, and good high temperature volume stability. Widely used in coal gasifier lining material and coal water slurry pressurized gasifier working face lining.
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High chrome bricks are mainly composed of Cr203, monoclinic zirconia and alumina fine powder. Therefore, the performance of high chrome bricks is closely related to the performance of these substances. In general, the performance characteristics of high chrome bricks are mainly reflected in the following aspects:
(1) Excellent resistance to slag erosion. Cr203 material itself has excellent slag corrosion resistance, which is mainly due to the following points: 1) The solubility of Cr203 in coal slag is very low, thus ensuring the integrity of the material; The wettability is poor, thus delaying the dissolution of Cr2O3 in the slag; 3) After the Cr2O3 material dissolves into the slag, the viscosity of the slag will increase, and even a uniform protective layer can be formed on the surface of the material to block the pores of the material and inhibit the Slag penetration.
(2) Excellent high temperature performance. The melting points of Cr203, A1203, and Zro2, the main components of high-chromium bricks, are about 2400, 2050, and 2700 °C, respectively. After high-temperature treatment at 1700 °C, Cr2O3 and A12O3 form a well-crystallized and continuous aluminum-chromium solid solution, so high chromium Refractory materials have high high temperature strength.
(3) Excellent anti-scour performance. The formation of aluminum-chromium solid solution and the sintering effect of ZiO2 make high-chromium materials have lower apparent porosity and higher compressive strength (up to 150MPa or even 200MPa or more), so high-chromium refractories have good erosion resistance.
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(4) Thermal shock resistance and thermal peeling resistance. Due to the transformation toughening effect of ZrO2, the thermal shock resistance and thermal spalling resistance of high chromium refractories are improved.
Influence of operating temperature on the life of high chrome bricks.
How high temperature can high chrome refractory bricks withstand? The load softening temperature of high chrome bricks is greater than or equal to 1700 degrees, which means that high chrome bricks can be used for a long time in a high temperature environment of 1700 ℃ and below. The operating temperature has a great influence on the service life of high chrome bricks. The higher the temperature, the greater the damage rate and the lower the service life of the bricks. In the working environment of the coal-water slurry gasifier, the temperature will be reduced or significantly reduced due to high temperature. The essential reason for the service life of high chrome bricks is that high temperature changes or significantly changes the viscosity-temperature characteristics of cinders. The higher the temperature, the lower the service life. After long-term research and statistics of use results, above the appropriate operating temperature, the erosion rate of high-chrome bricks will increase by 4 times for every 100 °C increase or for every 44 °C increase, the brick erosion rate will increase by 1 time.
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The operating temperature is related to the ash melting point and viscosity of the coal, and the ash melting point and viscosity of the coal slag have a direct relationship with the coal slag component, 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 of the slag viscosity. The ash melting point of coal slag should be lower than 1300 ℃, and it should be controlled at 1250-1300 ℃. The viscosity should also be controlled in the appropriate range of 15-25 Pa·s, which can not only ensure that the slag forms an effective protective layer on the working surface, but also maintain A certain fluidity, does not block the slag discharge port. The viscosity at a suitable operating temperature is controlled between 25-35 Pa·s.
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