Disk reactor

Fig. 22. Schematics of chemical vapor deposition epitaxial reactors (a) horizontal reactor, (b) vertical pedestal reactor, (c) multisubstrate rotating disk reactor, (d) barrel reactor, (e) pancake reactor, and multiple wafer-in-tube reactor (38).

The finishing reactors used for PET and other equilibrium-limited polymerizations pose a classic scaleup problem. Small amounts of the condensation product are removed using devolatilizers (rotating-disk reactors) that create surface area mechanically. They scale as... 

Figure 2. Radial-axial velocity field and temperature contours for a rotating-disk reactor at an operating condition where a buoyancy-driven recirculation vortex has developed. The disk temperature is HOOK, the Reynolds number is 1000, Gr/Re / = 6.2, fo/f = 1.28, and L/f = 2.16. The disk radius is 4.9 cm, the spin rate is 495 rpm. The maximum axial velocity is 55.3 cm/sec. The gas is helium.

Cheong, S. I. and Choi, K. Y., Melt polycondensation of poly(ethylene terephthalate) in a rotating disk reactor, J. Appl. Polym. Sci., 58, 1473-1483 (1995). 

Fig. 6.12 Experimental smoke traces in a rotating-disk reactor, illustrating stable flow and buoyancy-induced instabilities [45]. When the disk rotation is too low for a given disk temperature, buoyancy can significantly interrupt the ideal flow patterns. Photographs courtesy of Drs. William Breiland and Pauline Ho, Sandia National Laboratories, Albuquerque, NM.

Consider a rotating-disk reactor that is designed to destroy CO on a catalytic surface. The CO is dilute in an air stream. Assume that the catalyst completely destroys any CO at the surface—meaning that the gas-phase mass fraction of CO at the surface is zero—and assume that there is no gas-phase chemistry. The CO2 that desorbs from the catalyst is so dilute in the air that its presence can be neglected. Thus the mass-transfer problem can be treated as a binary mixture of CO and air. Assume that the reactor is held at a fixed pressure of 1 atmosphere. 

Oxley P, Brechtelsbauer C, Ricard F, Lewis N, Ramshaw C. Evaluation of spinning disk reactor technology for the manufacture of pharmaceuticals. Ind Eng Chem Res 2000 39 2175-2182. 

Figure 9. Main design concepts for adiabatic reactors. A) Adiabatic packed-bed reactor B) Disk reactor C) Radial-flow reactor.

The three-stage rotating disk reactor is illustrated in Fig. 30. Each stage consists of one cylindrical and two conical elements and is connected to the next stage by another cylindrical element with a relatively small diameter. Fluid motion and gas dispersion are achieved by a rotating flat plate that contains holes at its outer edge to generate gas bubbles. The reactor can be used for cocurrent and countercurrent flow of gas and liquid or slurry. 

Fic . 30. Schematic diagram of three-stage rotating-disk reactor. (After Brauer, 1982. reprinted with permission from the Institute of Chemical Engineers.)... 

Important Design Characteristics ok Three-Stage Rotating-Disk Reactor (after Brauer, 1982)... 

Finally, the rotating-disk reactor provides efficient gas-liquid mass transfer by constant renewal of the gas-liquid film on the rotating disk. The mass-transfer coefficient in such a reactor can be calculated using Eq. (6.49). The reactor provides a low pressure drop and partially backmixed gas and liquid phases. The extent of backmixing can be further reduced by the use of baffles. Once again, power consumption and mechanical difficulties may limit the size of such vessels. 

The rotating-disk reactor is applicable for bulk polycondensation reactions such as those for the productions of Nylon 66 and 610, polyethylene terephthalate, polyurea, and polycarbonate. High agitation and multidisks provide a high rate of surface renewal, which increases the efficiency of the reaction process. 

Batch rotating disk reactor TiOj-UV-A Laboratory Hamill et al. (2001)... 

The Spinning Disk Reactor - Studies on a N ovel TiOi Photocatalytic Reactor, Chemo-sphere 42 397-403. 

Most industrial processes using the interaction of fluids to obtain chemical changes can be classified into one, or sometimes more of the preceding five liquid reactor types. Variations on these themes are used for gas-gas, gas-liquid, or gas-solid reactions, but these variations parallel many of the processing ideas used for liquid-liquid reactors [20]. A new continuous, spinning disk reactor concept has recently attracted interest for some intrinsically fast organic reactions and for possible application in crystallizations [21]. Modular microreactors have also become of interest to fine chemicals producers and pharmaceutical companies for their faster reactions, ease of scale-up, and low cost [22]. 

Contactors in which the liquid flows as a thin film Packed columns Trickle bed reactors Thin film reactors Rotating disk reactors... 

The concept of process intensification aims to achieve enhancement in transport rates by orders of magnitude to develop multifunctional modules with a view to provide manufacturing flexibility in process plants. In recent years, advancement in the field of reactor technology has seen the development of catalytic plate reactors, oscillatory baffled reactors, microreactors, membrane reactors, and trickle-bed reactors. One such reactor that is truly multifunctional in characteristics is the spinning disk reactor (SDR). This reactor has the potential to provide reactions, separations, and good heat transfer characteristics. 

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