Mixer-reactors, microstructured

Production operation (1700 kg h" ) of a microstructured mixer-reactor for high-value polymer intermediate product (FZK works) [17]... 

The first start-up of the plant was in June 2005 [67]. A temperature diagram shows that most of the heat is released in the retention time tube (see Figure 5.33). The temperature measured directly at the outlet of the microstructured mixer-reactor StarLam 3000 was below 50 °C even at higher throughputs. During the retention time, tube temperatures up to about 130 °C were reached. The throughputs for this first test mn were increased in three steps to up to 3600 kg/h. 

Microstructured Mixer-reactors for Piiot and Production Range and Scaie-out issues... 

Caterpillar microstructured mixer-reactors owe their name to their total micro-channel shape, characterized by alternately up- and down-lifting ramps at the floor and ceiling of the fluid path, which as a whole resemble the fringes along the body... 

Microstructured Mixer-reactors for Pilot and Production Range and Scale-out Issues 89... 

M 39] [P 37] Using an azo-type competitive reaction, the selectivities were compared for the P- and V-type micro mixers having straight and oblique fluid injection, respectively [41]. In this way, laminar- and turbulent-flow mixing achieved by vertical interdigital microstructured mixers can be compared. The selectivities of the turbulent V-type mixer are better to some extent as compared with the P-type device however, neither approaches the characteristics of the ideal tubular reactor. The micro devices, however, are better than a conventional jet mixer. 

Figure 5.32 StarLam 3000 microstructured mixer retrofitted to existing plant peripherals and tank reactor (by courtesy of Wiley-VCH Verlag GmbH) [67],...

The inlet pipes of the two starting reactants to the batch vessel were simply connected to the StarLam mixer [67]. The only difference to the previous feed lines was the installation of filter cartridges before the entries to the microstructured mixer, necessary to avoid blocking of the reactor. The pressure drop in the lines was lower than 3 bar so that it was possible to keep the pumps used before in the plant. At the outlet of the reactor, a tube reactor was installed. During optimization it was found that it is sufficient to insulate this tube to reach the temperature needed to finish the reaction. The pipe ended directly in the batch vessel where the second endothermic reaction step was carried out as before. 

For many reactions, the microstructured mixers are simply followed by tube reactors, e.g., double-mantled tubes or shell-in-tube heat exchangers. The benefit from mixing in combination with the benefits of the continuous-flow process through the tube give process intensihcation, while providing reliable operation, especially when for larger volume flow ranges. 

As mentioned above, radial mixing is crucial to get narrow RTD. Therefore, the use of passive mixer helps equalizing the radial concentration in the laminar flow domain. It is known that static mixer allows to obtain narrow RTD in tubular reactors even with high viscous media [18]. The beneflcial effect of radial mixing can also be expected in microstructured mixers. Boskovic et al. [19,... 

Schwarz et al. [85] studied the efficiency of different microstructured mixers followed by microchannels and their influence on the space time for obtaining high product yields. With increasing mass transfer performance of the micromixer and decreasing channel diameter of the microchannel reactors, shorter reaction times of several minutes at lower reaction temperatures compared to conventional batch reactor were obtained. Similar observations are reported for the synthesis of biodiesel in capillary microreactors [86] and in zigzag microchannels [87]. 

Of course, the mixing quality is a very important parameter for microstructured liquid-liquid reactors. There are some approaches to characterize the mixing quality of such devices. Up to now, the most important method for characterizing the mixing quaUty of micromixers is the Villermaux-Dushman reaction [5]. This is a two-reaction system with a fast and a very fast reaction, which has been adapted for use with microstructured mixers. The better the mixing, the less product of the slower reaction is formed. This product (I3 ) is easily detected by UV spectroscopy. 

In recent years, research activities have paid increasing attention to reactions on a very small scale. The development of manufacturing technology has also enabled the production of miniature components for chemical reactor technology. Microstructured or microchannel reactors are called microreactors. They can also be defined as miniaturized reaction systems. The channel dimensions in microreactors are typically 50 Jim to 2 mm. Microreactor manufacturers provide microstructured mixers, heat exchangers. 

Similar optimization studies were done for the reduction step. Therefore, a cooled, freshly prepared ozonolysis reaction mixture was fed to microstructured reactors and contacted with a NaBH4 solution (3.5 M in DMF). For completion of the reduction, the microstructured mixer was connected to a residence time module (5 ml internal volume, LTF) (www.ltf-gmbh.com), as the rate of the reduction reaction is clearly slower than that of the ozonolysis. Within the scope of tested microstructured reactors, again the five-channel mixer by mikroglas (www. mikroglas.com) performed best. 

Five different types of reactors, including tube reactors, static mixers and a microstructured reactor, were tested for the synthesis of an intermediate to 3deld a quinolone antibiotic drug, named Gemifloxacin (FACTIVE ) [13,14]. 

A chip-type micro reactor array comprises parallel mixer units composed of inverse mixing tees, each followed by a micro channel that it is surrounded by heat exchange micro channels (so called channel-by-channel approach similar to the tube-in-tube concept). Such an integrated device was developed as a stack of microstructured plates made of a special glass, termed Foturan (Figure 4.26). The integrated device was attached to PTFE tubes of various lengths. 

Reactor type Caterpillar mini mixer-tube reactor, 1st generation Microstructure in one plate initial depth maximum depth 600 pm 850 pm... 

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