Wiped-film reactor

V-(6-Methyl-2-pyridyl)aminomethylenemalonate (1001, R = Me, R1 = H) was cyclized to 1,8-naphthyridine (1003, R = Me, R1 = H) in 70% yield in a continuous-operation wiped-film reactor with control of the residence time, whereas in a conventional wiped-film reactor, the yield was 25-30% (79MI2). On heating in dodecylbenzene or in diethyl phthalate at 285-300°C for 3-6 min, the yield was 90% (73MIP3). 

A polymerization reaction is normally followed by two principal separation processes elimination of monomers or diluents, and separation of solid polymers. The residual monomer content is often removed by the devolatilization. When this is important, extruders, tower, and wiped-film reactors are used (e.g., for certain step-growth polymerizations to very high conversion). 

Stage including cage reactors, rotating disk reactors, wiped film reactors and extruder type reactors. 

Polymerization in the final stage, where special wiped film reactors are used. Temperatures aroxmd 350°C and a vacuum of about 1 mm Hg are maintained. 

In the final stages of polymerization, in fact, mass transfer of the condensation product must always be considered. Commercially, the reaction is then carried out in special wiped-film reactors. The final transport equations can be numerically solved, and among the various reaction parameters, the film surface area is found to be the most important. The average chain length, ii , at the end of the reactor is found to increase with increasing up to some critical value beyond which the overall polymerization becomes reaction controlled. 

Wiped film stills in place of continuous still pots —Centrifugal extractors in place of extraction columns —Flash dryers in place of tray dryers —Continuous reactors in place of batch —Plug flow reactors in place of CFSTRs —Continuous in-line mixers in place of mixing vessels... 

Bashkar et al. 160 Continuous Polycondensation, finisher Tube reactor, wiped film... 

The Eastman process has operated in Texas (USA) with three continuous, stirred-tank reactors, a wiped-film evaporator, a distillation train and a continuous, counter-current, liquid-liquid extractor for recovery of the catalysts since 1996 (1400 metric tons per year capacity, e.g., semiworks facility), but full commercial capacity has not yet been reached. The main problem is still the formation of oligomers. Another answer to the problem of IL loss to the organic phase consists in the extraction of the products from the IL using a supercritical fluid [101], but operational costs are high. 

Bhaskar, V., Gupta, S. K. and Ray, A. K. (2001). Multi-objective optimization of an industrial wiped film poly (ethylene terephthalate) reactor some further insights, Comput. Chem. Eng., 25, pp. 391-407. 

Packed column, trickle-bed reactor, film reactors (falling film, agitated film, scraped/wiped film), rotating disk (or rotating... 

Flowsheets for processes are sometimes generated without following the hierarchy of properties described previously. As an example, Siirola [20] proposed a reactive-distiUation solution to make methyl acetate. Unit operations that combine the property differences present abrupt departures from common methodologies. With the advent of various pieces of equipment, such as differential side-stream feed reactors (i.e., semicontinuously fed batch reactors), continuous evaporator-reactors (e.g., wiped-film evaporators), and reactive distillation columns, one can consider these unit operations in the development of conceptual designs. As an example, Doherty and Malone [21] have presented systematic methods for reactive distillation design. 

The agitated thin-film reactor was an 0.08 m diameter wiped-film evaporator and was cooled by either convection or evaporation. Because of vacuum requirements for evaporation of the solvent, only convective cooling was utilized. Yields were found to be 10 to 15% higher than in the 250 L stirred tank. The increase in temperature affected the results far less than that which occurred in the stirred tank. Although no exact data on local energy dissipation rates in wiped-film evaporators was available for the unit, higher local energy dissipation rates occurred than in stirred tanks. 

If the heat rise in the tubnlar reactor (nnspecified) could not have been tolerated, the wiped-film evaporator with more effective convective heat removal (since more surface area to volume is achieved) would have been required. 

Resolution A static mixer reactor was superior to a wiped-film evaporator in yield. Heat removal was accomplished in a subsequent flash vessel. 

In wiped-fihn reactors, thin films are generated in order to facilitate mass transfer of the condensation product. Because the diameter of the drum in which the film is generated is usually large, we can ignore its curvature, treating it approximately as a flat film. 

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