Refractory castables have been widely used in fluidized bed furnaces, and compared to lining constructed with various shaped bricks inside the furnace, the service life of the furnace lining can be extended by about one year. Nowadays, most boiling furnaces in China choose to use refractory castables as the main lining material. What are the types of castables used in boiling furnaces, including high aluminum castables, clay castables, lightweight insulation castables, etc.
At present, the construction plan for replacing the original refractory brick furnace lining with high aluminum casting material is as follows:
1. Boiling furnace top design
① The shape of the refractory brick furnace top is conical, and the angle between the arch and the horizontal brick is designed to be 10 °. For safety reasons, a 15 ° angle is used;
② The thickness of the furnace top still adopts a refractory brick thickness of 230mm;
③ The ring beams and arches are not reinforced, and the ring beams are poured in nine sections. Expansion joints between each section are filled with 6mm asbestos boards;
④ The arch is composed of 12 fan-shaped surfaces, with 3mm asbestos board filled between the 12 joints. To reduce the excessive thrust of the arch on the ring beam due to high temperature, 6mm asbestos board is filled between the two to provide cushioning.
⑤ There is no asbestos board pasted around the arch ring beam, and the 120mm well platform at the top outlet is poured separately.
⑥ Due to the change in the angle between the cone and the top, in order to ensure the insulation effect at the top, a 10 # channel steel is used as a lifting ring for the top cover, raising it by 100mm
2. Construction steps and methods
① Construction shall be carried out in the order of ring beam first and top cover later. The top cover shall be poured diagonally to prevent deformation of the formwork.
② The surface of the template is coated with oil and coated with asbestos boards with reserved expansion joints to prevent moisture from being absorbed by the template and to facilitate demolding. The template requires a tight fit and no water leakage to prevent water loss and affect the strength of the material
③ Mix materials near the construction site with a water cement ratio of 12%, and use them once.
④ Use an insertion vibrator to compact the pouring material to a sufficient degree, preferably when the surface is no longer sinking.
3. Maintenance and oven drying
Before opening the furnace, strict oven maintenance work must be carried out to discharge free water and chemical crystallization water from the casting material, and to avoid sudden temperature changes during the ignition and heating process that may cause explosions. When drying the oven, control the heating rate between 25-50 ℃/h, strictly control the constant temperature stage during the heating process, and avoid uneven distribution of oven temperature.
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