In dry coke quenching devices, the use of refractory materials is crucial. They are not only related to the operating efficiency of the equipment, but also directly affect production safety and product quality. The following is a detailed analysis of the use of refractory materials in dry coke quenching devices:
I. Overview of dry coke quenching devices
The dry coke quenching device is mainly composed of a dry quenching furnace, a primary dust collector, a boiler, a secondary dust collector, a coke discharge device and a circulating fan. Among them, the dry quenching furnace is the core equipment. Its masonry belongs to a vertical kiln structure. It is a cylindrical upright masonry in a positive pressure state. The furnace body is divided into a pre-storage section, a ramp area and a cooling section from top to bottom.
II. The use of refractory materials and performance requirements
Pre-storage section
Upper cone top area: This part has a large temperature change before and after coke loading, and is also subject to great wear by coke. Therefore, mullite-silicon carbide masonry with good erosion resistance, wear resistance, rapid cooling and heating resistance and high flexural strength is selected.
Solid refractory brick masonry in the middle straight section: To withstand the thermal expansion generated by the loading of red coke, as well as the impact and wear of the coke, A-type mullite bricks with high strength, wear resistance, and good resistance to rapid cooling and heating are selected for masonry.
Lower annular flue: It is divided into two annular masonry of inner wall and outer wall. The inner wall must withstand the impact and wear of the coke, and must also prevent leakage due to the pressure difference between the pre-storage section and the annular flue. Therefore, A-type mullite bricks with grooves and tongues are also used for masonry.
Inclined channel area
The bricks in the inclined channel area are cantilevered layer by layer to support the load of the upper masonry. The temperature fluctuates frequently, and the circulating gas carries coke dust to produce fierce scouring of this part. Therefore, mullite and silicon carbide bricks with good thermal shock resistance, wear resistance and flexural resistance are selected for masonry.
Cooling section
Although the straight section refractory brick masonry of the cooling section has a simple structure, its inner wall refractory brick masonry is one of the most vulnerable parts because it has to withstand the intense wear when the coke flows downward. Therefore, B-type mullite bricks with high strength, wear resistance, and good resistance to rapid cooling and heating are selected.
Other key parts
Furnace mouth: Use B-type mullite silicon carbide bricks and mullite silicon carbide fire clay.
Primary dust collector: Considering the double erosion and wear of circulating gas and coke powder, high-strength wear resistance and good resistance to rapid cooling and heating are selected.
Cooling room: Use B-type mullite bricks, dense clay bricks, mullite fire clay and wear-resistant castables.
Other high-temperature sections: Use heavy high-aluminum castables and lightweight high-aluminum castables.
III. Performance characteristics of refractory materials
Mullite products: have good chemical stability, small thermal expansion rate, strong thermal shock stability, and strong resistance to acid and alkali slag erosion. Its high-temperature spiral deformation resistance is much higher than other ordinary high-aluminum bricks including special high-aluminum bricks, and its high-temperature performance is comparable to some properties of silicon, magnesium, and corundum products.
Silicon carbide material: It has the advantages of good wear resistance and corrosion resistance, high high-temperature strength, high thermal conductivity, small linear expansion coefficient, and good thermal shock resistance. But the disadvantage is that it is easy to oxidize at high temperature and is not suitable for use in an oxidizing atmosphere.
IV. Precautions for the use of refractory materials
Structural design: Improve the structural design of the ramp area and reasonably distribute the support bearing pressure to ensure the cooling capacity of the coke and the effective increase of the bearing area of the bracket.
Masonry standards: When laying refractory materials for the dry quenching furnace, strict management should be implemented, masonry standards should be implemented resolutely, the masonry of the flue flat arch ring beam should be reasonably mastered, and the gravity surface of the supporting bracket should be evenly distributed to make it evenly stressed.
Operation system: Improve the operation system, maintain stable working conditions, reduce the gap between materials in the furnace, maintain a stable coke discharge volume, and ensure the uniformity of material flow.
Gas-to-material ratio: Use a reasonable gas-to-material ratio to reduce the resistance of the circulation system and slow down the scouring of the refractory by the airflow.
Maintenance times: Try to reduce the number of maintenance times for complete cooling of the red coke in the CDQ furnace to ensure thermal balance and reduce the damage caused by thermal expansion and contraction of the refractory.
The selection and use of refractory materials in the CDQ unit is a systematic project, which needs to be reasonably configured according to the working conditions and performance requirements of different parts. At the same time, attention should also be paid to the protection and maintenance of refractory materials to extend their service life and improve the operating efficiency of the CDQ unit.
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