Coke oven refractory.
In modern coking production, coke ovens present the following characteristics: first, large volume, large weight and long life; Second, the single coke oven has a large amount of refractory, which is the furnace type with the highest proportion of refractory materials for high-temperature furnaces and kilns, accounting for more than 80% of the overall coke oven weight; The energy consumption of the coking process accounts for 13% and 15% of the energy consumption in the steel industry. Therefore, the technological progress of coke ovens is inseparable from the technological progress of refractories.
The refractories for daily maintenance of coke ovens can be divided into silica bricks, with scale quartz as the main crystalline phase, siliceous refractory products used for masonry coke ovens, and also used to repair furnace walls; Iolite furnace door bricks, made of iolite firing, are also used to repair furnace doors; Grouting material, the main component is phosphoric acid + clay material + water, which is used for furnace top sealing; Ceramic fiber rope is used to plug leaks in furnace walls; 901 slurry is used to pour the furnace cover; Ceramic fiber blanket is used for environmental protection plugging of coke ovens; High-temperature rubber sheet, the main component of which is high-temperature resistant rubber, is used to repair furnace doors.
Coke oven refractory technology direction.
At present, the selection of coke oven refractories basically adopts the following standards: carbonization chamber combustion chamber side wall, water discharge in the coking process, refractory materials that are easy to hydrate are not suitable for use, and almost all countries in the world choose siliceous refractories. The bottom of the carbonization chamber has the same thermal expansion rate, bears the large weight of coal and coke and the friction of the coking process, and should be selected with high strength and wear-resistant refractories. The top of the carbonization chamber is affected by the covering layer above it and the static and dynamic load of the coal loading car, and the refractory with high strength and wear resistance should also be selected. The furnace door lining of the carbonization chamber and the furnace head at both ends of the carbonization chamber, due to the frequent opening of the furnace door, the temperature drops from about 1000 to below 500, and it is advisable to use high aluminum refractory materials with good thermal shock resistance and high load softening temperature. In the inclined flue area, it is not in contact with coal and coke, and the working temperature is slightly lower than that of the combustion chamber, so it is advisable to choose siliceous refractories. The side walls on both sides of the regenerator have a large temperature difference between cold and hot alternation, so it is advisable to use high-quality clay bricks. Regenerator lattice bricks, non-load-bearing structure, should have high heat storage capacity and thermal shock resistance, should be used clay bricks.
At present, the furnace door of the carbonization chamber is commonly used to seal the glaze furnace door bricks, the furnace door is easy to adhere to heavy tar, difficult to clean, and the furnace door is easy to break. The side wall of the combustion chamber of the carbonization chamber is made of silica bricks, which is heated and expanded, and the damage is serious when pushing the coke, which is easy to cause the furnace wall to leak, which not only affects the quality of the coke, but also seriously affects the life of the coke oven, and increases the maintenance time and cost of the coke oven. Zero-expansion silica bricks can be used in this part, which greatly reduces the thermal expansion pressure, and has a higher density, which is not easy to cause leakage of the furnace wall.
The overall development of coke oven refractories presents the characteristics of personalized customization, high purity, densification, precision, popularization of carbon-containing refractories, composite and amorphous of oxide and non-oxide materials. The direction of its technology development is considered from the beneficiation, purification and homogenization on the one hand, and how to prepare aluminum-silicon refractories from low-grade raw materials on the other hand.
Coke oven refractories have great potential for energy saving and emission reduction.
At present, the conventional refractory configuration of coke ovens is as follows: siliceous materials are used for furnace tops, furnace bottoms, ramps, regenerators, heating walls, coal-loading holes, and fire-viewing holes, clay bricks are used for furnace roofs, regenerators, coal-loading holes, and fire-viewing holes, and iolite, mullite, andalusite, and sillimanite are used for furnace doors.
Over the years, China's coke oven technology has been continuously improved. However, in terms of refractory technology, traditional refractory materials are still used, but the standard is improving, especially in the energy saving and environmental protection of coke ovens, refractories have not played their due technical potential.
In order to meet the development requirements of coke ovens, domestic production, learning, research and use departments have jointly developed new refractory materials and technologies such as high-density silica bricks, composite prefabricated parts, composite ceramic materials on the surface of silica bricks, new materials for furnace bottoms, homogeneous and homogeneous siliceous fire clay, electrofusion (low expansion) silica bricks for thermal repair, and new technologies for thermal maintenance of coke ovens, which have been widely and effectively used.
For example, the strength of the new coke oven refractory high-density silica brick is 1 of that of ordinary silica brickAbout 5 times. Its porosity is low, and the thermal conductivity can be increased by more than 20% compared with the traditional coke oven silica brick, which can reduce the fuel consumption of the coke oven, reduce the emission of pollutants such as NOx, and save energy and protect the environment. Under the same conditions, the use of high-density silica bricks can effectively increase the production capacity of coke ovens. The domestic use of nanotechnology makes silica brick products retain the basic properties of siliceous materials while improving the density, thermal conductivity and anti-wear performance of bricks. The reason for this is that the dispersion properties of nanoscale mineralizers are much better than those of conventional mineralizers. Its application makes the main crystal phase and matrix of the refractory more tightly bonded, reduces the porosity of the product, and improves the homogeneity of the product.
Under the same working conditions, when ordinary silica bricks are changed to high-density silica bricks, the heat transferred to the carbonization chamber should be the same in one cycle, and only the temperature of the fire path in the combustion chamber will be changed. Therefore, when the thermal conductivity of high density silica brick is 2At 33 (w m·k), the flame temperature in the combustion chamber can be reduced by 46. It can be seen that the use of high-density silica bricks can theoretically reduce the temperature of the flame in the combustion chamber, which is conducive to reducing fuel consumption, thereby saving energy and reducing emissions.