What is the main reason for the crushing of coal particles in the fluidized bed?

　　After the coal particles enter the circulating fluidized bed boiler, the particles are quickly heated, and the volatilization of the coal particles generates internal pressure. If the internal pressure exceeds the particle's bearing capacity, bursting occurs. In addition, the uncertainty of the particle shape makes the local heating of the particles uneven and generates thermal stress, which is also the reason why the primary burst happens. The volatilization analysis shows that the coke particles after the first burst will continue to burn. Due to the inhomogeneity of combustion and the collision between the particles, the coke particles will continue to fragment.