Page 190 - Design of Simple and Robust Process Plants
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5.5 Intensification of Process Functions  175
                   A rotating machine was developed as the heart of an absorption heat pump by
                 Ramshaw and Winnington (1997) at ICI, and-later at the University of Newcastle
                 and at Interotex Lim. The development focuses on a double-effect absorption heat
                 pump and is intended for use in small-scale air-conditioning and refrigeration
                 plants. Field tests of this equipment are currently under way.
                   Rotational particle separators for dust and mist streams of particle sizes >0.1 lm
                 have been described by Brouwers (1996). The core component of the rotational parti-
                 cle separator is the filter element, which consists of a multitude of small axial chan-
                 nels rotating around a common rotational axis. The gas streams flow axially through
                 these channels, where the particles are centrifuged against the wall. The gases leave
                 the channels, while the particles are collected at the walls where they are periodically
                 removed at high velocities.
                   Reactive stripping in a rotating packed bed has been used in the production of
                 hypochlorous acid at Dow Chemical (Trent et al., 1999). This problem was recog-
                 nized as an opportunity to utilize centrifugal techniques by virtue that although the
                 reaction employed:
                   NaOH + Cl 2 ® HOCl + NaCl
                 had rapid kinetics, the HOCl produced was subject to undesirable decomposition to
                 chlorate. The key to the development of the process was the rapid transfer through
                 the maximum decomposition pH zone, which maximized stripping of the HOCl to
                 the vapor phase. The solution to the problem was found in a rotating packed bed
                 which moved liquid through a porous packing while the gas moved countercur-
                 rently. This resulted in an industrial application with the design principle of a rotat-
                 ing packed bed that could be applied to different separations, including gas/liquid
                 or gas/liquid/solid, absorption, and adsorption (Figure 5.27).


                                                  Liquid outlet

                       Gas out let





                 Liquid                                   Driver
                 inlet
                             Seal

                                                       Packed bed
                       Gas flow

                       Liquid flow
                                      Gas inlet
                 Fig. 5.27. Rotating Packed bed applicable for fast; G/L and F/L/
                 S reactions, absorption, adsorption.
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