The actual operation data related to mass balance in the 350 MW circulating fluidized bed(CFB) boiler of Hepo Power Plant were systematically investigated. The change relation of operation parameters of large-scale CFB boiler were obtained

under normal operation conditions with different loads. The change rules of temperature and pressure inside the furnace when the boiler ran at full load were analyzed

and the average material concentration in the furnace under normal operation conditions of large-scale CFB boiler was ascertained. The results show that

when the generation power was increased from 170 MW to 300 MW

the pressure difference in cyclone separator increased from 0.30 kPa to 1.05 kPa. When the unit load was rose further

the pressure difference changed little. As the generation power was increased

the temperature at the furnace bottom/outlet and at the return valve increased linearly. For large-scale CFB boilers

when the average material concentration in the furnace reached 3 kg/m~3

it meets the mass balance requirements and satisfies the demands for normal operation of the CFB boilers.