The circulating fluidized bed boiler is a kind of new boiler with high efficiency and low pollution. There are about 1,600 circulating fluidized bed boilers in China. A wide range of low quality coal can be used in this kind of boiler. It has strong load capacity and the combustion is stable. In addition, its low-temperature combustion characteristics can effectively curb the emission of nitrogen oxides and desulfurization can be achieved in the furnace. Thus, it is the preferred boiler for domestic and foreign combined heat and power generating units. Special furnace lining of this kind of boiler has a very high requirement to the refractory material. The common circulating fluidized bed boiler furnace wall is divided into igniter, ignition duct, wind chamber, hearth, hearth outlet flue, whirlwind separator, dipleg, return feeder, wind pipe, front flue roof of the superheater and the tail flue. Here we focus on the whirlwind separator. Separators are available in a variety of forms. The traditional design has a variety of forms such as whirlwind separation, blinds separation, planar flow separation and trough separation. Most of the current high temperature separation uses whirlwind separation. High temperature whirlwind separator is divided into adiabatic and cold (or cold air) separator. At the inlet of the high temperature whirlwind (or adiabatic) separator, the working temperature is generally about 900 degrees, the flue gas flow rate of 15-25m / s and the ash concentration is high. The refractory material at this position should have good abrasion resistance and thermal shock resistance. So far, the boiler manufacturers and refractory manufacturers adopt high-strength wear-resistant construction. In the actual boiler operation, the service cycle of the wear-resistance of the boiler lining is short. In general, the castable is worn within 1-3 years. Seriously, it will break or fall off, which should be removed and re-built.