Heat scraped surface reactor

Scraped surface horizontal film (votator) Especially for viscous feed. OK for foaming, for fouling, crystal formation and suspended solids. Viscosities > 2000 mPa s. Relative to agitated film retention time of 1 1 and volume 1 1. Overall heat transfer coefficient 2 kW/m °C decreasing with increasing viscosity. Power 3 to 12 kW/m. Related to scraped surface reactor. Section 6.20. 

Scraped surface heat exchangers (SSHE) have been used as tubular reactors for plastics pyrolysis. SSHE overcome coking and carbon deposits forming on heat exchanging surfaces when the plastic pyrolyzes to hot gases. A tubular reactor with a special internal screw mixer has been developed in Poland [5]. The purpose of the specially shaped internal mixer is to mix the molten plastic and to scrape coke from the internal surface... 

Knowledge about the mechanism of deposition of corrosion products onto the fuel rod surfaces is still limited. The dissimilar elemental concentrations for the brushed and scraped fractions in the filter/demineralizer plants are probably due to the fact that these two fractions were created by different mechanisms. The brushed fraction most likely results from the deposition of suspended particles from the reactor water, while the scraped fraction is assumed to be formed by precipitation of dissolved corrosion product species. The axial distributions of both fractions of the deposits on the fuel rod surfaces usually show differences which also suggest that they were generated by different mechanisms. The brushed fraction shows a characteristic profile, in which the corrosion products deposit preferentially near the bundle inlet and which can be correlated with the fluid shear at the heat transfer surface. This distribution is consistent with the assumption that particle deposition is the predominant mechanism for the buildup of the loosely-adherent deposits, since low fluid shear favors particle deposition. On the other hand, the axial profile of the tenacious fraction is quite different, being relatively constant over the middle region of the bundle and decreasing towards each end. 

The heat exchanging surface of the extruder is relatively large compared to various other reactors. Also, due to its functioning as a scraped heat exchanger, the thermal homogenization of the product is reasonable. 

---