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Show 100 \f'- J 90 l) ." 80 ~ C..D. .C.O 70 CD 1 c CD 60 CJ ~ ~ • 50 ......... c ~ 0 ~ -.ii.i 40 CD '0 > 30 ~ c 0 0 20 ~ 0 o ___ .0' .... , I './ * .."",,- • •• I / .. rf ~ •• • I • I / • v· • ... t" ~ •• /i •• • • • *,v , W l 0 •• I • _Il _A I ~ ~ • "" . ..- •• .-' I ~ • ".' • /._ ..... /N ••• •• /"-~/..~~ •~ V ,~ ••• / ./ ~~ I •• / ~ .'"' .' I l / • ~ 10 J • • •• 04~ •••• ••• ••• o ,--~I 350 400 450 500 550 600 650 700 750 800 Temperature Degrees F Figure 8 - NOx Formation with Nitrogen Compounds Temperature Degradation Any discussion of catalyst degradation is incomplete without mentioning the problem associated with temperature. As temperatures on the surface of the catalyst are increased, a corresponding increase is seen in the tendency of the fmely dispersed catalyst to agglomerate and form larger sections of active sites. This agglomeration has the effect of lowering the overall availability of active sites and thus lowers the activity of the catalytic system. This process is minimal in many systems that operate at low outlet temperatures; however, with systems handling difficult VOC constituents requiring higher inlet temperatures, the outlet temperature can sometimes reach the upper limit, typically 663-C, (122S-F), the catalyst life is severely limited. This can usually occur in applications where the inlet loading of VOC is uncontrolled and variable, and can increase the reaction rate, causing the temperature excursions. Manufacturers now support catalyst designs capable of continuous operation at 732-C, 13S0-F. 9 |
