A modelling study on the dose rate effect on the efficiency of the EBDS-process (ES-VERFAHREN)

Electrons penetrating gas create inhomogeneous dose distributions by their interaction with gas molecules. This behaviour becomes more pronounced for decreasing electron energies. Thus, according to dose rate measurements for electrons from 300 kV scanners, dose rates up to 150 Mrad/sec may occur. A computer model of the homogeneous gas phase reactions of the electron beam dry scrubbing (EBDS) process has been developed. The model is capable of handling dose distributions which involve high dose rates. This is accomplished by a modulation of the dose rate between zero and a preset maximum, while keeping the total applied dose constant. Extensions of this model allow the treatment of 3-dimensional dose distributions. The calculations show that radical concentrations are correlated both to dose and dose rate. With increased dose, more NOsub(x) is removed from the flue gas, while the dose rate has no effect on removal efficiencies calculated with a system of homogeneous gas phase reactions. A similar result is obtained for the radiation induced SO2-H2SO4 conversion. (author)