The wear of circulating fluidized bed refractory materials is the result of the combined action of multiple factors. Here are some of the main reasons:
1. Flue gas flow rate:
The flue gas flow rate is the main factor affecting the wear of the furnace inner wall. The greater the flow rate, the greater the kinetic energy of the fly ash particles, and the more ash particles impacting the furnace inner wall per unit time, resulting in increased wear.
2. Fly ash concentration:
The level of fly ash concentration is directly related to the concentration of solid particles in the flue gas in the furnace. A higher fly ash concentration means that more particles will impact the furnace inner wall, increasing the risk of wear. Especially when the fly ash circulation rate is high, although it can improve the combustion efficiency and heat transfer effect, it will also aggravate the wear of the furnace inner wall.
3. Fly ash particle characteristics:
The hardness, temperature, shape and particle size of the fly ash particles will also affect the degree of wear. The larger the particle, the higher the hardness, and the more irregular the shape (such as angular), the greater the impact force generated during the collision, and the more serious the wear on the refractory material.
3. Heating surface and lining material: The wear resistance of the material is also an important factor affecting the amount of wear. Under the same conditions, the better the wear resistance of the material, the less wear. Conversely, materials with poor wear resistance will wear faster under the same working conditions.
4. Unreasonable design structure: If the design structure of the boiler is unreasonable, such as the number of grab nails and brick hooks is small or unevenly distributed, and the grab nails are not pre-treated as required before construction and pouring, it may cause a large area of wear-resistant materials to fall off, thereby aggravating wear.
5. Poor construction process: The construction process of the castable will also affect the wear resistance of the refractory material. For example, if the reserved expansion joint does not meet the requirements or there are problems with the expansion joint design, it may cause large pieces of wear-resistant materials to fall off during operation.
6. Thermal stress and thermal shock: Temperature cycle fluctuations and thermal shock can cause cracks and peeling of refractory materials. Especially when the combustion conditions change during the start-up and shutdown of the boiler and operation, the temperature in the cyclone separator changes significantly and the lining temperature also changes significantly. This temperature change will cause internal stress between the lining aggregate and the binder due to the different thermal expansion coefficients, thereby destroying the overall structure of the refractory and wear-resistant plastic lining.
7. Chemical erosion:
The harmful impurities (such as sulfur, nitrogen, etc.) in the raw coal will produce acidic gases such as sulfur dioxide and nitrogen oxides during combustion, which will chemically erode the refractory and wear-resistant materials. In addition, the penetration of alkali metals may also cause the deterioration of refractory materials and the reduction of physical and chemical properties.
The wear of circulating fluidized bed refractory materials is the result of the combined action of multiple factors. In order to reduce wear, it is necessary to start from multiple aspects, such as optimizing boiler design, improving construction process quality, selecting materials with good wear resistance, and strengthening operation management.
HOME