The life of steel fiber wear-resistant castables is not only determined by their own performance indicators, but also by the construction quality and furnace performance. In the construction of CFB boilers, the following key details should be paid attention to:
Preparation Before Construction
Check the model and performance indicators of the steel fiber wear-resistant castable to ensure that the steel fiber is not rusted, the castable is not damp, and it is stored in a sealed manner.
Remove oil stains, welding slag, etc., sandblast the surface to enhance the bonding strength; weld anchor nails on the metal base (spacing 200~300mm), and apply a special interface agent.
Mixing and Proportioning
Accurately weigh the castable, steel fiber and water (or binder) according to the mix ratio provided by the manufacturer, and the water-cement ratio error should not exceed ±0.5%. The amount of steel fiber added is usually 1%~3% of the castable weight, and it needs to be evenly sprinkled to avoid agglomeration.
Use a forced mixer to stir the dry material for 2~3 minutes, then slowly add a certain amount of water, and continue stirring for 5~8 minutes until the material is uniform, without agglomeration, and the steel fiber is well dispersed. Avoid excessive stirring that may cause the steel fiber to bend or the castable to set prematurely, and avoid insufficient stirring that may cause uneven strength.
Construction Points
When the thickness exceeds 300mm, the layer should be divided into layers, with each layer thickness ≤150mm, and the layers should be roughened; vibrate until there are no bubbles, and avoid over-vibration.
The spacing is 3~5m, the seam width is 5~8mm, and ceramic fiber ropes are filled to ensure penetration.
The steel fiber in the scouring area can be increased to 5%, and the corners are reinforced with prefabricated parts.
Maintenance and Demoulding
Within 24 hours after pouring, cover with plastic film or wet sack to keep moisture, avoid direct sunlight or wind, and the curing period is not less than 7 days. Water spraying can be used for curing in high temperature environment, but the temperature difference between the water temperature and the surface of the castable should not exceed 15℃. During the curing period, collision or load application is strictly prohibited to avoid cracking of the castable surface.
Quality and Safety
Test compressive strength (≥80MPa), wear resistance (≤3.0kg/m²), and perform flaw detection on key parts; use 310S steel fiber in high temperature areas, wear dustproof equipment during construction, and recycle waste.
In the construction of CFB boilers, the steel fiber wear-resistant castable needs to be strictly controlled from the whole process including material management, base treatment, mixing and vibration, maintenance and testing, etc., with particular attention paid to the reinforcement measures in the high-temperature wear area and the temperature and humidity control of the construction environment, so as to ensure that the castable forms a uniform and dense wear-resistant layer and extend the operation cycle of the CFB boiler.