Method for correlating weathering data on adsorbents used for the removal of CH3I

Traditionally, weathering data have been expressed in terms of removal efficiency as a function of time for a select number of bed depths. Variables include: (1) variations in the efficiency of the adsorbent when new; (2) guard bed design (bed depth, replacement schedule); (3) air quality; and (4) air velocity. This paper discusses the development of a single parameter, namely, the Effective Weathering Rate (EWR), its usefulness in correlating weathering data, and subsequent utilization during design. The effectiveness of the model was checked by analyzing several sets of data. Values of EWR were determined from the limited available experimental data for air which could be described only qualitatively as ranging from relatively clean to relatively dirty air from a heavily industrialized area. As quantitative data become available, it is expected that the EWR can be correlated with the character and concentration of air contaminants such as hydrocarbons, SO2, NO/sub x/ and O3. The EWR, determined from experimental data, can be used to predict adsorber efficiencies for conditions corresponding to a specific application. Some of the changes in conditions which can be treated by this method include: (1) bed depth of adsorbent, (2) addition of guard bed or depth of guard bed, (3) effectiveness of the carbon (new), (4) operating time, and (5) air velocity. Someparametric studies were performed analytically to demonstrate some applications of the weathering model. These included calculating the adsorber efficiency as a function of time and bed depth, for carbons having various efficiencies when new, and for guard beds of variable bed depth and having different replacement schedules for the guard bed material