Sonochemical reactors scale

Gogate PR, Pandit AB (2004) Sonochemical reactors Scale up aspects. Ultrason Sonochem 11 105-117... 

Gogate PR, Mujumdar S, Thampi J, Wilhelm AM, Pandit AB (2004) Destruction of phenol using sonochemical reactors scale up aspects and comparison of novel configuration with conventional reactors. Sep Purif Technol 34 25-34... 

Pandit and co-workers have shown that scale-up may be possible on a more rational basis if cavitation is employed, and some data have been reported by Pandit and Mohalkar (1996), Mohalkar et al. (1999), Senthil et al. (1999), and Cains et al. (1998). A variety of reactors can be used, viz. the liquid whistle reactor, the Branson sonochemical reactor, the Pote reactor, etc. The principal factors affecting the efficiency of a hydrodynamic cavitation reactor are irreversible loss in pressure head and turbulence and friction losses in the reaction rates. 

At times the net rates of chemical/physical processing achieved using ultrasonic irradiations are not sufficient so as to prompt towards industrial scale operation of sonochemical reactors. This is even more important due to the possibility of uneven distribution of the cavitational activity in the large scale reactors as discussed... 

Dahlem O, Demaiffe V, Halloin V, Reisse J (1998) Direct sonication system suitable for medium scale sonochemical reactors. AIChE J 44 2724-2730... 

Gogate PR, Mujumdar S, Pandit AB (2003) Large scale sonochemical reactors for process intensification Design and experimental validation. J Chem Tech Biotech 78 685-693... 

Keil F, Dahnke S (1997) Numerical calculation of Scale Up effects of pressure field in sonochemical reactors - homogenous phase. Hung J Ind Chem 25 71-80... 

Asakura Y, Nishida T, Matsuoka T, Koda S (2008) Effect of ultasonic frequency and liquid height on sonochemical efficiency of large-scale sonochemical reactors. Ultrason Sonochem 15 244-250... 

Sonochemical reactors can be used to degrade a variety of contaminants in aqueous solution, including some very harmful and recalcitrant compounds such as chlorinated hydrocarbons. The scale-up of these reactors in order to meet industrial needs (i.e., faster rates and high volume processes) is the present challenge in the development of the technique. The many advantages of the technique, described in this chapter, will surely encourage researchers and engineers to face some unsolved problems in the future, in order to provide alternatives to conventional waste treatment. 

Destaillats H, Lesko TM, Knowlton M, Wallace H, Hoffmann MR. Scale-up of sonochemical reactors for water treatment. Ind Eng Chem Res 2001 40 3855-3860. 

Li, C. Z., Yoshimoto, M., Ogata, H., Tsukuda, N., Fukunaga, K., and Nakao, K. 2005. Effects of ultrasonic intensity and reactor scale on kinetics of enzymatic saccharification of various waste papers in continuously irradiated stirred tanks. Ultrasonics Sonochem.,12, 373-384. 

The unique reaction environment generated in sonochemical reactors has been shown to greatly enhance reaction rates for a variety of chemical transformations. However, the commercial scale application... 

Large-scale batch sonochemical reactors can be designed on the basis of the performance of conventional laboratory sonicators if it is assumed that there are no serious scale-up factors. These are the cleaning bath reactors (indirect sonication) and reactors with immersible transducers or sonic probes (direct sonication). Continuous reactors use either wall-mounted transducers (indirect sonication) or sonic probes (direct sonication). 

Considering the specific apphcation of chemical synthesis, the presence of solid catalyst (particles/salts in a typical concentration range of 1 to 10% by weight of the reactants optimization is recommended in the majority of the cases using laboratory-scale studies) in the sonochemical reactors results in intensification due to the following mechanisms ... 

Ajaykumar, P.R. Gogate and A.B. Pandit, Mapping the efficacy of new designs for large scale sonochemical reactors Ultrason. Sonochem., Accepted for Publication, (2005b). 

Table 10.10 Some large scale sonochemical reactors...

Large-scale ultrasonic irradiations are extant technology. Liquid processing rates of >200 L/min are routinely accessible from a variety of modular, flow reactors with acoustic powers of tens of KW per unit (14). The industrial uses of these units include 1) degassing of liquids, 2) dispersion of solids into liquids, 3) emulsification of immiscible liquids and 4) large-scale cell disruption. While these units are of limited use for most laboratory research, they are of potential importance in eventual industrial application of sonochemical reactions. 

Solutions to the problem of the scale-up of sonochemical reactions do exist but they are not so simple as the use of bigger versions of laboratory equipment. In a production situation the volumes treated vill be very much larger than those considered in the laboratory and the type of process vill govern the choice of reactor design. It could well be that some processes would be more suited to low intensity sonication (e. g. using a bath type reactor) whereas others may need higher intensity irradiation via a probe type system). 

The first step in the progression of a sonochemical process from laboratory to large scale is to determine whether the ultrasonic enhancement is the result of a mechanical or a truly chemical effect. If it is mechanical then ultrasonic pre-treatment of a slurry may be all that is required before the reacting system is subjected to a subsequent conventional type reaction. If the effect is truly sonochemical, however, then sonication must be provided during the reaction itself. The second decision to be made is whether the reactor should be of the batch or flow type. Whichever type is to be used there are only three basic ways in which ultrasonic energy can be introduced to the reacting medium (Table 10.9). Several different types of ultrasonic reactors are currently available (Table 10.10). 

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