Real-time diagnosis of circulation stability for CFB combustion optimization using a novel image trajectory method

Abstract

A novel particle image trajectory method was developed to determine the velocity of particles entering a cyclone particle separator in a typical circulating fluidized bed (CFB) incinerator burning biomass and industrial waste. Based on particle velocity, the mass recirculation ratio was calculated to characterize the fluidization stability, and its key factors were quantitatively discussed. The results indicated that the proposed method can determine the particle velocity and recirculation ratio rapidly and accurately, and the relative errors of velocity calculation were 4.07 % and 0.04 %. The time lag between the recirculation ratio and the cyclone negative pressure, furnace temperature, and secondary air was 20–70s. We observed that the cyclone negative pressure was most likely related to circulation stability after eliminating the time lag. The longest time lag was between the recirculation ratio and boiler load, which was 230 s. The correlation between the recirculation ratio and boiler load improved (0.220) after the time lag was eliminated. Furthermore, the recirculation ratio could characterize changes in the boiler load in advance and provide predictive information for boiler load feedback control, which can be useful for monitoring and controlling incinerator combustion.