Stacked-platelet reactor

Housing-encased Single-platelet and Multi-platelet Stack Micro Reactors... 

Figure 3.7 Alternated 90° turned adjacent platelets forming a stacked cross-flow configuration. Image of thermally bonded devices (top). Complete mounted multi-plate stack micro reactors (bottom) [45].

The reactor can be obtained in many materials such as aluminum alloys, copper, silver, titanium and stainless steel. The number of stacked platelets, the dimensions of the micro channels on the platelets and the fluidic connectors were also varied. Pressure tightness up to 25 bar and He tightness were demonstrated, although this is certainly not the upper limit. 

Figure 3.14 Ceramic platelet micro reactor bottom housing with recess for platelet stack, platelets and top plate [54],...

GP 2] [R 2] Initial work with a steel multi-plate-stack micro reactor with micro-structured platelets made of polycrystalline silver (OAOR modified) confirmed a selectivity of up to 49% at conversions of about 12% (3 vol.-% ethylene, 50 vol.-% oxygen, balance nitrogen 5 bar 41 h 277 °C) [4, 26, 40]. 

For a short description of the aims of experimental concentration cycling with respect to citraconic acid formation, see [13]. It is also demonstrated there that the response to rectangular concentration pulses for a given reactor configuration of a multi-channel-stack micro reactor can be improved by increasing the number of platelets and channels (while reducing their diameter). Such behavior was shovm for an incompressible fluid, i.e. is not solely related to the above-mentioned reaction. 

The design of multichannel micro reactors for gas-phase reactions is typically based on a stack of micro structured platelets. For strongly endothermic or exothermic reactions, it lends itself to alternate between layers of reaction channels and heat-... 

One of the most frequently used micro reactor types relies on the use of micro-structured platelets with multiple parallel channels, typically manufactured by methods other than routinely used for chip processing, encased in a housing [3,4, 12, 13, 18, 28-39]. If more than one platelet is used, which is usually done to increase throughput, a stack-like arrangement is preferred for parallel feed. Such stacks are either welded directly from the outside [29, 30], are encompassed by a cover [3,18, 31, 32, 37-39], have end caps with fluidic connectors [12,13, 33] or are inserted into a recess of a housing, which is typically composed of two parts [4, 28, 34-36, 40 1]. 

Reactor type Multi-plate-stack in cylindrical housing Outer platelet dimensions (length No. I No. II No. Ill) = reaction channel length 12.5 mm 37.5 mm 50 mm... 

Reactor type Multi-plate-stack with counter-flow guidance Total number of reaction platelets 6 10... 

GP18][R6] Experiments atfixedfiiowrate allowed a comparison of reactor performance over a VO /Al203 catalyst of a multi-platelet-stack micro-channel reac-torandaconventionalfixedbedasafunctionoftheinlettemperature[133,134j. 

Reactor type Multi-plate-stack in cylindrical housing Platelet material Aluminum... 

Figure 3.18 Schematic view of the reactor module consisting of a stack of metallic frames (a). Single catalyst carrier platelet (b) [51] (by courtesy of SCS).

Modular multi-plate stack reactor [46-48] This modular reactor concept was developed for flexibility, ease of handling and fast change of parameters. It contains five assembly groups, which are microstruc-tured platelets, a cylindrical inner housing, two diffusers and a cylindrical outer shell with a flange. The reactor module can be equipped with a fixed-bed catalyst or with a stack of microstructured wafers... 

The Caterpillar micro mixer is an example of a simple, pilot-sized micro mixer-tube reactor that has an internal microstructure with a ramp-like shape inducing recirculation flow patterns, whereas the overall channel structure can be kept fairly large. The volume varies between 1 L/hr to several hundred liters per hour. Several hundreds of precision-engineered, star-shaped platelets can be stacked, and the flow can be distributed. 

Early studies with the detailed description of the so-called microstructured reactors (microreactors) are dated 1986 however, theoretical calculations of scientists of the former GDR were not put into practical application (1). A patent of that time describes, very generally, a miniaturized chemical engineering apparatus and systems made by simple fabrication methods. A stack-like arrangement of platelets carrying microchannels and fluid connecting structures was also proposed. 

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