Film formation in a horizontal twin-shaft rotating disk reactor for polymer devolatilization

•We study the film formation process in a twin-shaft rotating disk reactor.•CFD based on VOF can predict the film thickness distribution.•The overlapping zone affects greatly the film formation process.•The scraped film is much thinner and more uniform than the free film.•The disk clearance significantly influences the scraped film thickness.

Film formation characteristics in a horizontal twin-shaft rotating disk reactor for polymer devolatilization have been investigated by means of experiment and computational fluid dynamics (CFD). Volume of fluid (VOF) model has been used to simulate the film formation process and predict the film thickness distribution on the rotating disks, validated experimentally by electrical conductance method. The mechanism for the film formation in twin-shaft rotating disk reactor is different from that in single-shaft reactor, due to the effect of overlapping zone between two adjacent disks. There are two kinds of films generated in the reactor. The free film, greatly affected by the liquid viscosity and rotating speed, shows the similar characteristics with that in the single-shaft reactor. The scraped film, generated by overlapping zone, is much thinner and more uniform than the free film for highly viscous liquid. Compared with the viscosity and the rotating speed, the disk clearance plays a more significant role in determining the thickness and the shape of the scraped film.

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