Prediction of emission gas concentration from pressurized fluidized bed combustion (PFBC) of coal under dynamic operation conditions

Emission of CO, NOx, N2O and SO2 from a 71 MW PFBC was continuously observed for 8 days while the plant load, the level of coal load, the concentration of emission gases, total pressure, and temperature varied dynamically. Prediction of concentrations of such gases are attempted in this paper to prove the high accuracy of a series of ASHTR equations proposed in previous papers ([1] Tsuji Y, Tazawa K, Abe R, Sasatsu H, Harada T. Behavior and estimation of nitrogen oxides emission in 71 MWe PFBC boiler. Journal of the Japan Institute of Energy 1999:78(3):191–200. [2] Abe R, Sasatsu H, Harada T, Misawa N, Tsuji Y, Gotou H. Emission of SO2 and desulfurization mechanism in 71 MWe PFBC demonstration plant. Journal of the Japan Institute of Energy 2000;79(1):57–68. [3] Tsuji Y, Abe R, Gotou H, Sasatsu H, Harada T, Misawa N. Interaction among emission gases in 71 MWe PFBC demonstration plant. Journal of the Japan Institute of Energy 2000 (in press)) using cyclone gas temperature (Tc). The correlation observed in the present study verified the principle of ASHTR equations where Le Chatorie principle is assumed applicable to the reactions in the cyclone to determine the compositions of emission gases because cyclone gas temperature appeared to govern major reactions. However, during part load operation, the emission of N2O and SO2 concentrations showed several spikes in the same profile, which did not relate to Tc, and was found to have strong relation with the inverse of the temperature in the bed (Tb). Thus, rapid response to control the emission gases of dynamic change can be possible by controlling the temperatures of the bed to adjust the coal feed, feed water supply and bed height.