Particle fouling at hot reactor walls monitored In situ with a QCM-D and modeled with the frequency-domain lattice Boltzmann method

Abstract

Fouling at a hot reactor wall during emulsion polymerization was studied in-situ with a quartz crystal microbalance with dissipation monitoring (QCM-D). Transient maxima in resonance bandwidth were observed, which are typically interpreted as the signature of a coupled resonance. However, the most common type of coupled resonances, the film resonance, cannot explain these observations, because the film resonance should occur first on the high overtones (on the overtones with small wavelength). In experiment, the low overtones reach the maximum first. The maximum in dissipation can be explained with the particulate nature of the sample. As the particles flatten out and merge, the height of the layer decreases and the surface becomes smoother. The decreasing height lets the layer go through the film resonance in reversed order. Also, the decreasing roughness lets the bandwidth decrease, unrelated to the film resonance. The argument is substantiated with a simulation based on the frequency-domain lattice Boltzmann method (FD-LBM). Apart from explaining the features seen in QCM experiments on particle fowling, this case study demonstrates the capabilities of FD-LBM.