Application 1040

The importance of baffles in a reactor vessels

baffle (noun)

: a device (such as a plate, wall, or screen) to deflect, check, or regulate flow or passage (as of a fluid, light, or sound)

Can you use a rotating bed reactor (RBR) in any type of vessel? Absolutely.

Would the performance be higher with baffles in the vessel? Definitively.

A vortex, which forms due to the rotation of an agitator, is detrimental to the mixing in a reactor vessel. If the agitator is a rotating bed reactor, it also disrupts the flow through the RBR. Baffles are features in the reactor vessel that break the circulating flow pattern, preventing vortex formation and improving overall mixing.

The importance of baffles has long been established for stirred tank reactors with agitation by impellers, and baffling is equally important for vessels with an RBR installed. You don't need to take our word for it; customers that have investigated the effect of baffling on their mass-transfer limited reactions have found the same result. The most recent data comes from research at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB. They started out with the RBR S3 in a smooth glass vessel. After observing a deep vortex, drawn down into the RBR, and the resulting disappointing performance, one simple flat-blade baffle was installed. The performance for the enzymatic reaction was quantified with and without the flat-blade baffle, and the result is presented in the figure below. As seen in the data, installing one simple baffle resulted in a doubled yield at each time point on average.

The double-walled glass vessels (V2 and V3) that SpinChem offer are custom-made to fit the RBR S2 and S3 respectively. The vessels have structured inner glass walls that serve as "flower-shaped" baffles, which do not take up the same space as traditional flat-blade baffles. This minimizes the required volume of reaction medium, and maximizes mixing performance.

 

Flower baffled reaction vessel from SpinChemSome non-baffled vessels perform as if they had flow breakers installed, just through the shape of their vessel walls. For instance, any non-round geometry such as rectangular IBC-tanks may provide satisfactory mixing and prevention of a deep vortex forming. On benchtop scale, the round beaker is appealing with its simplicity, but a baffled reaction vessel will yield much better performance.

If you have more questions about this contact us.

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