Global market competition, increase in energy and other production costs,
demands for high quality products and reduction of waste are forcing
pharmaceutical, fine chemicals and biochemical industries, to search for
radical solutions. One of the most effective ways to improve the overall
production (cost reduction and better control of reactions) is a transition
from batch to continuous processes. However, the reactions of interests for
the mentioned industry sectors are often slow, thus continuous tubular
reactors would be impractically long for flow regimes which provide
sufficient heat and mass transfer and narrow residence time distribution. The
oscillatory flow reactors (OFR) are newer type of tube reactors which can
offer solution by providing continuous operation with approximately plug flow
pattern, low shear stress rates and enhanced mass and heat transfer. These
benefits are the result of very good mixing in OFR achieved by vortex
generation. OFR consists of cylindrical tube containing equally spaced
orifice baffles. Fluid oscillations are superimposed on a net (laminar) flow.
Eddies are generated when oscillating fluid collides with baffles and passes
through orifices. Generation and propagation of vortices create uniform
mixing in each reactor cavity (between baffles), providing an overall flow
pattern which is close to plug flow. Oscillations can be created by direct
action of a piston or a diaphragm on fluid (or alternatively on baffles).
This article provides an overview of oscillatory flow reactor technology, its
operating principles and basic design and scale - up characteristics.
Further, the article reviews the key research findings in heat and mass
transfer, shear stress, residence time distribution in OFR, presenting their
advantages over the conventional reactors. Finally, relevant process
intensification examples from pharmaceutical, polymer and biofuels industries
are presented.
Oscillatory flow chemical reactors
