Mixing-sensitive reactions reactor design

CVD reactions are most often produced at ambient pressure in a freely flowing system. The gas flow, mixing, and stratification in the reactor chamber can be important to the deposition process. CVD can also be performed at low pressures (LPCVD) and in ultrahigh vacuum (UHVCVD) where the gas flow is molecular. The gas flow in a CVD reactor is very sensitive to reactor design, fixturing, substrate geometry, and the number of substrates in the reactor, ie, reactor loading. Flow uniformity is a particulady important deposition parameter in VPE and MOCVD. 

Similarly, when moving from the pilot plant to manufacturing, a process engineer will either choose an existing vessel or specify the design criteria for a new reactor. A necessary condition for operation with a specified reactor temperature profile is that the required jacket temperature is feasible. We have therefore chosen to focus on heat transfer-related issues in scale-up. Clearly there are other scale-up issues, such as mixing sensitive reactions. See Paul [1] for several examples of mixing scale-up in the pharmaceutical industry. 

Many reactions involve shear-sensitive materials, which severely limit the maximum mixing rate and make impeller and reactor design important. Mixing becomes the limiting factor. 

REACTOR DESIGN FOR MIXING-SENSITIVE HOMOGENOUS REACTIONS... 

The kinetic simulations of the pulse combustor ignition can be carried out under conditions which closely approximate those in a continuously stirred tank reactor (cstr). In those calculations, hot product gases are steadily mixed with cold, unbumed reactants until the mixtures ignite. The reaction mechanisms used are valid for high temperatures, and the most important, sensitive reaction is reaction (3), and the combined influences of chemical kinetics, acoustics, and fluid dynamics can all be incorporated into a coherent practical design model [20]. 

Reactor Design for Mixing-Sensitive Homogeneous Reactions... 

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