Numbering-up concept

The numbering-up concept demands achieving absolutely uniform flow equi-partition by placing special headers in front of the parallel micro channels [5]. Although this has been solved for tubes in conventional multi-tubular reactors, the expenditure for equipartition in micro channel stacks is assumed to be higher, since the small channels may have more relative differences in structural preci-... 

Transfer from laboratory to industrial process - numbering-up concept... 

Different methods for scale-out have been collected and presented (Lob et al. 2006a). The two main methods are a smart scale-up, at best after having intensified the process, or the internal numbering-up concept. The first route was shown long ago by the Merck production case for an organometallic reaction, changing from micro- to mini-mixers (Krummradt et al. 2000). This route seems to be feasible, as long as... 

There are a number of further advantages to the numbering-up concept. Research results can be transferred into production faster, plants can be constructed in a shorter time, and the production capacity can be adjusted more flexibly to variations in demand. Since mass production of microdevices may result in relatively a low cost per piece, novel cost-saving maintenance and repair concepts based on disposable elements might be introduced. 

The estimated output of the laboratory-scale microreactor for pigment synthesis is about ltyear . To increase the output to lOtyear and to demonstrate a simple scaling up without redesign of the process, a pilot plant based on the numbering-up concept is realized (Figure 16.5). 

A yield of 95% was obtained by a micromixer-based process (<10s, at —10°C), whereas the industrial batch process (6 m stirred vessel) had only 72% yield (5 h, at —20 °C) [68]. The lab-scale batch process (0.51 flask 0.5 h, at —40 °C) had 88% yield (see Table 9.4). Pilot-scale studies followed with a homebuilt minimixer for reasons of clogging, which was not decisive at the lab scale. With one minimixer at the pilot scale, a yield of 92% was obtained (<10s, at — 10°C). The validity of the numbering-up concept was proven by operating also five minimixers of the same type at a yield of 92% (< 10 s, at —10 °C). This was the central part of the actual production process, running for more than 3 years until the life cycle of the commercial product of the corresponding multistage process run out (see Figure 9.34). 

First indications showed that the reactor performed as designed and that the numbering-up concept worked satisfactorily. 

The development of a microreactor for a retrofit of a fine chemical production at DSM Linz was described. Its success was strongly dependent on the good cooperation between DSM linz and FZK-IMVT, which initially led to the first micro reactor design and subsequently facilitated design modifications. Also, application of the numbering-up concept for direct scale-up of laboratory-scale experiments facilitated application on the production-scale tremendously. 

Poly methyl methacrylate (PMMA) formation Micro-mixer with 36 microchannels 25 pm width. Fouling problems reduced, improved polymer uniformity, scale-up by numbering up concept... 

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