Rotating packed beds

Figure 13.6 HiGee technology for hypochlorous acid manufacturing at Dow Chemical. Three rotating packed beds shown in front offer the same production capacity as the conventional plant behind them. (Courtesy Dow Chemical.)...

Table 13.1 Comparison between the reactive precipitation of CaCOs in conventional equipment and in rotating packed bed reactor.

Static mixing catalysts Operation Monolithic reactors Microreactors Heat exchange reactors Supersonic gas/liquid reactor Jet-impingement reactor Rotating packed-bed reactor... 

Compact heat exchangers MicroChannel heat exchangers Rotor/stator mixers Rotating packed-bed Centrifugal adsorber... 

Figure 1 Schematic of gas continuous operation of a rotating packed-bed gas/ liquid contactor.

Understanding the flow of liquid and gas through a rotating packed bed is important to understand the performance results achieved. Liquid flow involves two... 

Rotating packed-bed devices handle high volumes of fluids in a small equipment volume, compared to packed towers, due to the acceleration of gravity. The Sherwood flooding correlation for packed towers (25) is expressed as a plot of... 

Developing correlations to describe mass transfer in rotating packed beds has proven to be a challenge. Penetration theory (31), film-flow theory (32), and modified surface-renewal theory (12) are some examples of leveraging previous work... 

Gas-side mass transfer in rotating packed beds does not show the same level of enhanced performance as liquid-side mass transfer. Average volumetric gas mass transfer values for a wire screen packing increased with gas flow rate but decreased with increased rotor speed. Compared to a packed tower, the RPB... 

Heat input or removal in rotating systems is best accomplished using plates to separate the heat transfer fluids from the process fluids (45). Since spinning disc technology is discussed in Chapter 3 of this book, this section will cover only the application of heat transfer in conjunction with rotating packed beds and some of the issues related to further development needs. 

The higher heat transfer coefficients experienced by Hickman led to the concept of placing a peripheral reboiler and core condenser on either side of a rotating packed bed (50). This concept would be useful for distillation applications that need reflux and boilup. The internal exchangers as part of the rotor would decrease the required heat transfer surface area but would involve additional design and fabrication complexity. 

A number of parameters can be considered for scale-up of rotating packed beds, including rotor packing, liquid distribution, flooding, pressure drop, rotor speed, HTU, NTU, temperature, and pressure. Since the same packing material (same... 

These two successful commercial applications of rotating packed beds prove that scale-up from pilot-scale equipment can achieve the desired process performance in commercial-scale operations. In addition, the mechanical reliability of the rotating equipment is in line with the experience with other rotating... 

Trent D, Tirtowidjojo D, Quarderer G. Reactive stripping in a rotating packed bed for the production of hypochlorous acid. In Green A, ed. 3rd International Conference on Process Intensification for the Chemical Industry. London BHR Group, 1999 217-231. 

Trent D, Tirtowidjojo D. Commercial operation of a rotating packed bed (RPB) and other applications of RPB technology. In Gough M, ed. 4th International Conference on Process Intensification in Practice. London BHR Group, 2001 11-19. 

Burns JR, Ramshaw C. Process intensification visual study of liquid maldistribution in rotating packed beds. Chem Engr Sci 51 1996 (8) 1347-1352. 

Basic A, Dudukovic MP. Hydrodynamics and mass transfer in rotating packed beds. In Heat and Mass Transfer in Porous Media Conference Proceedings, 1992 651-662. 

Guo K, Guo F, Feng Y, Chen J, Zheng C, Gardner NC. Synchronous visual and RTD study on liquid flow in rotating packed-bed contactor. Chem Engr Sci 2000 55 1699-1706. 

Munjal S, Dudukovic MP, Ramachandran P. Mass transfer in rotating packed beds— II. Experimental results and comparison with theory and gravity flow. Chem Engr Sci 1989 44(10) 2257-2268. 

Lin CC, Chen YS, Liu HS. Prediction of liquid holdup in countercurrent-flow rotating packed bed. Trans IChemE 2000 78(Part A) 397 103. 

Burns JR, Jamil JN, Ramshaw C. Process intensification operating characteristics of rotating packed beds—determination of liquid hold-up for a high-voidage structured packing. Chem Engr Sci 2000 55 2401-2415. 

Basic A, Dudukovic MP. Liquid holdup in rotating packed beds examination of the film flow assumption. AIChE J 1995 41(2) 301-316. 

---