Rotating-cylinder reactor

A rotating-cylinder reactor is often used where the entire polymerization reaction chamber is rotated horizontally about its long axis while immersed in a constant-temperature bath. This requires only a minimum amount of stirring, or possibly no stirring at all. The particles would be kept in suspension strictly through the rotation of the reactor, which is variable over a small rpm range. 

The rotating-cylinder reactor is basically a piston/cylinder dilatometer. It can be filled completely with a swollen latex, eliminating any air-liquid interface. The variation of the latex volume as a function of temperature and degree of polymerization can be monitored continuously. A thermocouple is used to follow the latex temperature within the reactor. 

A cutaway drawing of the rotating-cylinder reactor is shown in Fig. 35. The mechanical aspects of the reactor system were designed to provide temperature control, fluid containment, and process measurements. The apparatus consists of a stainless steel (SS) holder and glass cylinder in which rides an SS piston, sealed by two Viton O-rings. Piston movements is monitored by a linear variable differential transformer (type 250 HCD, Schaevetz Engineering) attached to the piston and fixed relative to the cylinder. 

Fig. 35. Schematic diagram of the rotating-cylinder reactor. 1, thermometer 2, temperature controller 3, housing 4, reactor inlet bolt 5, stirrer 6, temperature sensor 7, bearing 8, temperature sensor wire leads 9, stirrer shaft belt 10, stirrer motor 11, reactor holder 12, reaction chamber 13, water jacket inlet 14, O-ring 15, volume sensor 16, volume sensor wire leads 17, rotating chamber belt 18, rotating chamber motor 19, base place 20, reactor outlet bolt 21, water jacket outlet. (Reprinted with permission from Chem. Eng. Sci. 43,2025, J. H. Kim, E. D. Sudol, M. S. El-Aasser, J. W. Vanderhoff, Copyright 1988, Pergamon Press pic.)...

Design parameters for novel reactors such as rotating-cylinder reactors, thin-film reactors, propeller loop reactors, screw reactors, and multidisk reac-... 

THE PROBLEM An undivided rotating cylinder reactor is operated in a batch recycle loop to process a batch of 0.2 m every 8 hours. The cylinder is 1 m long and 0.1 m in radius the interelectrode gap is 0.05 m. The reaction takes place under mass transfer limiting conditions. If the maximum rotation speed of the cylinder is 150 rpm, determine whether the operation is feasible if the required conversion is to be 80%. If so, what is the required rotation speed and what is the maximum conversion possible Assume that axial flow in the reactor can be ignored. The kinematic viscosity v is 1.1 X 10" m /s and the Schmidt number Sc is 2500. 

EXAMPLE 2.3. Mass Transfer Characteristics of a Rotating Cylinder Reactor with Axial Flow... 

The first of these reactions takes place at temperatures of about 150°C, the second reaction proceeds at about 550—660°C. Typical furnaces used to carry out the reaction include cast-iron retorts the Mannheim mechanical furnace, which consists of an enclosed stationary circular muffle having a concave bottom pan and a domed cover and the Laury furnace, which employs a horizontal two-chambered rotating cylinder for the reaction vessel. The most recent design is the Cannon fluid-bed reactor in which the sulfuric acid vapor is injected with the combustion gases into a fluidized bed of salts. The Mannaheim furnace has also been used with potassium chloride as the feed. 

Robinson and Walsh have reviewed earlier cell designs. The performance of a 500 A pilot plant reactor for copper ion removal is described. Simplified expressions were derived for mass transport both in single pass [243] and batch recirculation [244]. For a detailed discussion of the principle and the role of the rotating cylinder electrode reactor in metal ion removal the reader is referred to Refs. [13] and [241] (46 references). 

Walsh FC, The role of the rotating cylinder electrode reactor in metal ion removal in ref (23), p 101, and references therein... 

Robinson D, Walsh FC (1991) The performance of a 500 Amp rotating cylinder electrode reactor, Part 1. Current-potential data and single pass studies, Hydrometallurgy 26 93 Chem Abstr 114 (1991) 194767w... 

In order to determine the dynamics of atoms we have to carry out an inelastic neutron scattering measurement. With a reactor source this can be done with a triple-axis spectrometer, which has an analyzer crystal. Tripleaxis refers to the three axes for the monochromator, sample, and analyzer, all moving independently and controlled by a computer. With a pulsed source we use a mechanical chopper, which is a rotating cylinder with a hole perpendicular to the rotating axis that allows neutrons with a chosen range of velocity to go through. The neutrons scattered by the sample are detected... 

Reactor. Figure 1 shows a cross-sectional view of the aluminum alloy reactor. The rotating cylinder, 7, is 18 in. long by 10 in. diara., and the annular space, 6, (approx. 0.3 in. wide) is uniformly filled with a 0.75% Pt on AI2O3 reforming catalyst crushed and graded up to 40 to 60 mesh. Circular Teflon rings, 4,... 

High mass-transport coefficients are obtained in cells with a rotating cylinder electrode (RCE) and a small gap between the anode and the cathode, Fig. 4(a). High rates of mass transport are experienced in the turbulent flow regime, so that RCE reactors allow metal deposition at high speed, even from dilute solutions. RCE reactors have been operated at a scale involving diameters from 5 to 100 cm, with rotation speeds from 100 to 1500 rpm and currents from 1 A to 10 kA [79], It... 

Figure 9. A pilot scale rotating cylinder electrode reactor system for continuous extraction of cadmium powder from hydrometalliu gical process streams [40].

Several of these studies were conducted in an electrochemical batch reactor that had a rotating-cylinder anode (RCA). Since the anode was operated below the limiting current for mediator generation, relatively high coulombic efficiencies were achieved. Ion-exchange membranes were used to separate electrodes in Ag(II)-based processes, but were eliminated in processes based upon Co(III) and H2SO4. Rates of CO2 generation were measured and used to... 

Numerous treatability studies have been performed in small electrochemical batch reactors [13-15]. A typical batch reactor has a rotating cylinder anode (RCA) that is operated well below the limiting current for Ag(II) generation (Figure 4). The RCA enables the scientist or engineer to use a small apparatus to mimic mass-transport conditions in a pilot plant, without using massive flow-through electrochemical cells and pumps. 

Imamura et al. [28] describe a concentric cylinder reactor in which one cylinder is rotated. The axial flow rale and rotational speed are such to generate flows with Taylcn vortices which save to narrow the residence time and particle size distributions. The reactor is also claimed to be useful for continuous suspension polymerization. 

Figure 2.2 Elementary cell geometries (a) parallel-plate cell, (b) rotating cylinder in tube cell, (c) two plates in reactor cell, and (d) plate cell with non-parallel electrodes.

A rotating cylinder electrochemical reactor (RCER) for electrodeposition can be a single cell or as a cascade of cells (see Figure 11.4) on a common rotating shaft. 

Gahe, D.R. and Walsh, RC. (1990) Recovery of metal from industrial process liquors using a rotating cylinder electrode reactor. Institute of Chemical Engineering Symposium Series, 116, 219-229. 

Terrazas-Rodilguez, J.E., Gutierrez-Granados, S., Alatorre-Ordaz, M.A. et al. (2011) A comparison of the electrochemical recovery of paUadium using a paraUel flat plate flow-by reactor and a rotating cylinder electrode reactor. Eiectrochimica Acta, 56, 9357-9363. 

Alonso Alejandro R, Lapidus GT, Gonzalez I (2008) Selective silver electroseparation from ammoniacal thiosulfate leaching solutions using a rotating cylinder electrode reactor (RCE). Hydrometallurgy 92 115-123. doi 10.1016/j.hydromet.2008.02.001... 

For the rotating cylinder electrode to be adopted as a continuous reactor, some degree of axial flow has to be superimposed on the tangential and turbulent motion in the annulus (Fig. 2.8b). If the rate of mass transport due to axial flow exceeds that due to rotation then the reactor will exhibit approximate plug-flow characteristics. If the reverse is true the behavior will tend to approach that of a continuous stirred-tank reactor (see Section 5.1.1.1). 

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