A 300 MW circulating fluidized bed(CFB) boiler was simulated by computational particle fluid dynamics(CPFD) to investigate the reason of low frequency vibration of loop seal in the CFB boiler and reduce the possibility of low frequency vibration by optimizing the operating parameters of the loop seal. Firstly

for the low frequency vibration of the loop seal in the CFB boiler during operation

a full-scaled simulation of the CFB boiler was conducted to analyze the gas-solid flow inside the boiler. The pressure balance

material balance and solid volume fraction distribution inside the boiler were studied. The simulation results indicated that the root cause of the vibration of the loop seal was that the fluidized air velocity inside the loop seal was too high. It resulted in the occurrence of poor solid-phase transportation or even back-blowing

which caused the pressure fluctuation at inlet of the loop seal and vibration. Moreover

simulation of the loop seal component was conducted

the operating wind speed(return feed wind and loose wind) of the loop seal was adjusted linearly

the gas-solid fluid dynamics characteristic and solid circulation rate of the loop seal under different operating conditions were investigated

the basic data and operating characteristics of the loop seal under variable conditions were attained

and the appropriate operating wind speed interval of the loop seal was determined. Finally

the whole CFB boiler with optimized operating parameters of loop seal was simulated. The simulation results show that the CFB boilerran steadily. Especially

the pressure fluctuation at inlet of the loop seal obviously decreased and the low-frequency vibration of the loop seal was well controlled.