Page 191 - Design of Simple and Robust Process Plants

176 Chapter 5 Process Simplification and Intensification Techniques
Polymer devolatilization and pelletization have also been developed within a rotat-
ing packed bed, mainly as the result of increasing requirements for low residual
monomer levels within polymers. The technology (Cummings et al., 1999) is a com-
bination of a rotating packed bed and a centrifugal pelletizer, and was developed to
enhance mass transfer in order to improve polymer devolatilization. Combining the
two unit operations led to the creation of a device that was significantly smaller and
cheaper than existing solutions, and field testing of this unit is currently in pro-
gress.
A summary of process intensification is provided in Table 5.5.
Table 5.5. Summary of process intensification.

Process intensification Application

Build compact
Tilted plate separators Gravity and centrifugal separations
Heat exchangers Air separation
Mass exchangers Membranes for reverse osmoses, ultra-filtration,
membrane absorbers
Increase heat/mass/impulse
Transport
Static/vortex mixers Fluid mixing G, L, G/L, L/L
Pulse flow, self generating/induced Trickle flow reactors, extraction
Supersonic mixing
Centrifugal field
Cyclones G/S, L/S, L/L
Centrifuges/decanting centrifuges L/S, L/L
Rotating packed beds Reaction
Rotating packed bed Devolatilization
Rotational separators G/S, G,L particles/droplets <0.1 lm
Rotational de-sorber/de-aerator G/L
Rotating machine Absorption heat pump

5.6
Overall Process Simplification

Overall process simplification relates to a higher design level than has been describ-
ed above, and is based on the simplification and intensification of single units, or
the combination of functions such as reactive separation. The application of overall
process simplification is based on a review of the overall process for improvements,
and may be subdivided as:
1. Overall process design improvements
2. Single train design, scale-up of systems
3. Strategy around supplies and storage
4. Strategy around single component design