Spinning Disc Reactor SDR

Figure 3.1 Simplified scheme of a spinning disc reactor (SDR).

In order to improve the heat transfer in a reactor, use can be made of gravitational forces. This concept is used in the spinning disc reactor (SDR) as developed at Newcastle University. The reaction mixture flows in a thin layer in axial direction over a rotating disc. A typical heat transfer coefficient is 10 kW/m2K. This reactor however is dedicated for liquid-liquid reactions. Especially condensation reactions can be enhanced by removing the gaseous by-products thus shifting the chemical equilibrium to the right. 

The production process for polymers and the benefits that spinning disc reactor (SDR) technology can bring to it have been introduced in Chapter 5. In the following sections the use of SDRs for the manufacture of a specific polymer, polystyrene, is discussed, followed by data on polyesterification. 

Barium carbonate is used as a raw material for synthesising other ceramics used in electronics and magnetic materials. The opportunities for its use could be increased if an economical production route for the manufacture of fine BaCOj crystals could be developed. Tai et al. (2006) demonstrated the production of barium carbonate using a spinning disc reactor (SDR). 

Within the sector there is a mix of batch and continuous processes, the former offering flexibihty (possibly overcome in continuous mode using the spinning disc reactor (SDR)), and low-volume production. Where continuous processes can be improved using PI, and where batch operations can become continuous by using PI technology, the following benefits were seen for the company ... 

Stator-rotor spinning disc reactor (Stator-rotor SDR)... 

The spinning disc reactor (see also Chapter 5) was used by the company to produce an active pharmaceutical ingredient (API) that was required in the form of crystals with a specific size distribution (Oxley, 2000). The basis of the work was a 15 cm diameter spinning disc, on which crystalhsation was induced by adding an antisolvent. The improvements observed for the SDR output, in terms of crystal size distribution, are shown in Figure 8.19, where a comparison is made with the normal plant material. Overall, the PI solution compared to conventional production methods gave the following quantified benefits ... 

Pharmaceutical opportunity for the spinning disc reactor. Research at Newcastle University (Vicevic et al., in press) indicates that the use of the SDR for the catalytic isomerisation of oi-pinene oxide to campholenic aldehyde can be successful and can also minimise unwanted side reactions - a route, say the authors, to greener catalytic reactions - this follows on from the application reported in Section 8.4.6. 

Figure 10.6 Set-up for custard making on the SDR showing (left to right) 3.5 kW bath for disc pump for slurry custard slurry pumps for dye spinning disc reactor and SDR bath for walls (photograph courtesy of Protensive).

Schematic of SDR system Lid with viewing windows Spinning Disc, diameter D Reactor Vessel Injector (with stirrer option)...

It can be seen that the increment in polymerisation following one pass in the SDR corresponds with many minutes of reaction in the small batch reactor used as a reference. This is particularly encouraging because the mass transfer intensity in the laboratory stirred reactor is likely to be much greater than its industrial-scale equivalent, and it therefore provides a demanding benchmark for the spinning disc performance. 

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