MODEL EXPERIMENTS OF AUTOXIDATION REACTION FOULING .2. EFFECT OF FLOWPARAMETERS AND ANTIOXIDANTS

he effects of flow velocity and surface temperature on batch autoxidat ion fouling were studied using model solutions of indene in an inert l ubricating oil using an annular fouling probe where Re ranged from 300 0-6500 and T-surface ranged from 180-255 degrees C. Chemical initiatio n was used to overcome difficulties observed in thermally initiated ru ns. Fouling occurred in two stages: (a) an initial, linear fouling rat e which increased exponentially with temperature and decreased as Re i ncreased, consistent with a boundary layer reaction deposition mechani sm; (b) a subsequent, accelerated fouling stage involving bulk mass tr ansfer control. These mechanisms were also observed in model solutions of hexadec-1-ene and dicyclopentadiene in Paraflex. The effectiveness of an antioxidant, 2,6-dibutyl-4-methylphenol (BMP), in mitigating au toxidation fouling decreased markedly when exposed to temperatures abo ve its 'ceiling' temperature in the fouling loop. The antioxidant had little effect on autoxidation and fouling after the BMP was exhausted.