Reaction rotor-stator

The SDRs reported so far are mainly applicable to liquid reaction systems and their main limitations are short residence times and low production capacities. These problems are addressed by the so-called rotor-stator SDR, which allows a countercurrent gas-liquid contacting at higher throughputs and longer residence times [104]. 

Sparks, T. G., Brown, D. E. and Green, A. Assessing rotor/stator mixers for rapid chemical reactions using overall power characteristics (BHR conference series. Publication 18. Mechanical Engineering Publications Ltd. London, 1995). 

High-intensity inline devices are often used to mix fluids in the process industries. Such devices include simple pipes, baffled pipes, tees, motionless mixers, dynamic mixers, centrifugal pumps, ejectors, and rotor/stator mixers. In addition to their traditional application in physical processes such as mixing and dispersion, such devices can provide very effective environments for mass transfer and chemical reaction to take place. Furthermore, combining effective inline mixing with heat transfer is the basis of combined heat exchanger reactors (HEX reactors). 

Meeuwse, M., Lempers, S., van der Schaaf, J. et al. (2010) Liquid-solid mass transfer and reaction in a rotor-stator spinning disc reactor. Ind. Eng. Chem. Res., 49 (1), 10751-10757. Visscher, F., van der Schaaf, J. and de Croon, M. (2012) Liquid-liquid mass transfer in a rotor-stator spinning disc reactor. Chem. Eng. J., 185-186, 267-273. 

The stirred tank, of course, uses the stirrer for mixing, but the performance, even with modem designs of paddles, does little to ensure highly uniform reactions - the main point of stirring (or mixing) the fluid(s) within the pot . The most common types of mixers are in-line units and rotor stator mixers. Other mixer types considered below include variants based upon ejectors, fluidics, types using venturi aeration and ideas based upon spinning discs. 

The Taylor-Couette reactor (see Chapter 5) is also a rotor stator mixer, but is discussed separately. Units such as the Marbond HEX-reactor demonstrate mixing plus reactions plus heat transfer in one unit, and these are also discussed in Chapter 5. 

A preliminary test with a set of fast competitive reactions in a single-stage toothed rotor-stator mixer revealed significant fluid bypassing of the... 

Bourne, J. R., and M. Studer (1992). Fast reactions in rotor stator mixers of different size,... 

Note If this yield is still not being achieved, further work is necessary to determine the cause since further increases in mixing would not appear to be effective. A very high shear device such as a rotor-stator or Waring blender could be tested to determine if the reaction is still too fast (DaM too large) to realize the maximnm possible yield (minimum Xs). 

Figure 6-5(b) is a case for a reaction of unity, that is, all the pressure rise is in the rotor, with the stator blades acting only as guide vanes to deflect the gas. A reaction of unity is aerodynamically the equivalent of R = 0 or impulse, as shown at Figure 6-5(f) since it corresponds to an interchange of the moving and fixed blade row. 

Any effect of Mach number is experienced by rotor and stator equally and thus neither (or both) are limiting, and this Mach number will be lower than for other degrees of reaction under the conditions stated. If equal lift and drag are assumed in both rotor and stator, then optimum efficiency is obtained with R = 0.5 and VJu = 0.5. Although the latter is not always true, it does provide a useful criterion. Furthermore, the blade angles are similar in rotor and stator, which may be an advantage in the... 

Lactones have been used by Flechter, Dumur, Pollard, and Feringa [35] to conceive and set up a rotary motor that uses subsequent chemical reactions to achieve a 360° unidirectional rotation (Fig. 4). The stator is a naphthalene-derived unit connected in position 1 to a phenyl ring and bearing at position 2 a group that is transformed during the motions. The rotor is a 1,3-diphenol unit connected at position 2 to the stator. In the initial station 11 of the motor, one phenol group is... 

CDDM is shown in Fig. 3. The rotor (Fig. 3A) and stator (Fig. 3B) disks can be further modified to have microporous disks for simultaneous reaction and separation or an electric field can be applied across the disk clearance.Furthermore, the disks can have... 

When the rotor pole axis coincides with the axis of the stator coils the magnetic circuit seen by the stator has minimum reluctance. The reactance corresponding to the armature reaction in this rotor position is called the direct axis synchronous reactance Xs/- If the stator winding leakage reactance, Xa, is deducted from Xgd the resulting reactance is called the direct axis reactance X/. 

When the rotor poles are coincident with the stator coils axis the armature reaction is a maximum and the reactance is called the direct axis transient reactance X . 

Unfortunately, the available data are sparse at present. From the heat transfer point of view, the suitability of the reactors may be put in deceasing order as SSTR, stator-rotor SDR, HEX reactors, AFR, SDR, ACR/ATR, OBR and HIGEE. If the interphase transfer dictates the reaction rate, the volumetric mass-transfer coefficient plays a dominant role. The micro-mixing and residence time also are of importance in the case of fast reactions and thermally unstable products. The above ordering (but for the SDR) could be used for gas-liquid or liquid-liquid phases. If solid-liquid or solid-liquid-gas are involved, the decreasing order could be OBR, ACR/ATR, AFR, HIGEE, stator-rotor SDR, and SSTR. Studies are underway on the characteristics of the reactors. These would help to ascertain their relative merits quantitatively in the future. 

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