Construction and Maintenance of Wear-resistant Materials for CFB Boilers

In a CFB boiler, on the one hand, a large number of high-temperature solid particles moving at high speed continuously wash away the wear-resistant materials and destroy them; on the other hand, the wear-resistant materials crack and peel due to temperature fluctuations, thermal shock and mechanical stress in the furnace. At the same time, the penetration of alkali metals, etc. can also easily cause the failure and damage of wear-resistant materials.

In CFB boilers, the wear-prone areas mainly include the water wall and the heating surface arranged in the furnace, the separation return system, the tail flue inlet and the slag discharge system. The main areas where wear-resistant materials are used include the dense phase area of the furnace, the lower area of the furnace screen heating surface, the furnace outlet, separator, material legs, return valve, separator outlet flue and tail convection flue.

Construction and maintenance of wear-resistant refractory materials

1) Setting of expansion joints

The setting of expansion joints is very critical. Construction joints are also expansion joints. For areas where the castable area is too large, construction should be carried out alternately, construction joints should be left, and construction joints should be staggered.

2) Handling of metal anchors

Due to the difference in linear expansion coefficient between metal materials and wear-resistant materials after heating, it is necessary to apply asphalt on the surface of the metal material before construction of wear-resistant refractory materials. When applying asphalt, there should be a certain gap between the castable and the heating surface. The difference in thermal expansion of the heating surface during operation will not cause damage to the wear-resistant material.

3) Vibration

If the vibration is insufficient or not in place, the density of the wear-resistant castable cannot meet the requirements or is uneven, which may cause the castable to be insufficient in strength and difficult to play an anti-wear role. The formwork in locations that are difficult to construct should be as small as possible.

4) Thermal maintenance of wear-resistant refractory materials

Since the inorganic mineral raw materials contain a certain amount of water, a certain amount of water is added as a solvent during the preparation of the castable. This water needs to be discharged through natural drying and thermal curing. After thermal curing, all pouring holes opened in the sealed box need to be closed and welded, and all steam channels opened for thermal curing should be sealed and welded.