Process Intensification for Responsive Processing

Abstract

The era of responsive processing is upon us. It has emerged from the concepts of process intensiŽ cation (PI) and is aimed towards the development of processes which are more responsive to market needs whilst responding to changes in process parameters in seconds or milliseconds rather than several minutes or hours, as is typiŽ ed in a conventional process plant using traditional batch reactors with large inventory. In order to evaluate the degree of responsiveness of a process it is essential that intensiŽ ed modules are coupled with real time performance monitoring techniques with very fast response times. Advances in reactor and unit operation technology should go hand in hand with research and development in the analytical instruments and techniques. Non-evasive techniques for characterizing monitoring the speed of reaction should be used where ever possible. The perceived beneŽ ts of this technology are many and are appropriate for the processing industry, which is currently braced with extreme challenges and is striving for a competitive edge. Process  exibility, improved product quality, speed to market, just in time manufacturing, reduced foot print, improved inherent safety and energy efŽ ciency, distributed manufacturing capability and ability to use reactants at higher concentrations are some of the beneŽ ts of the proposed technology. In order to realize the beneŽ ts of responsive processing, intensiŽ ed heat and mass transfer modules, together with novel processing routes, will be required. Research and development work in this area has been going on for over ten years and in recent times industrial interest has gathered signiŽ cant momentum. Process intensiŽ cation was pioneered by Ramshaw in the 1980s and may be deŽ ned as a strategy which aims to achieve process miniaturization, reduction in capital cost, improved inherent safety and energy efŽ ciency and often improved product quality. In order to develop an intensiŽ ed process plant, it is essential that all the unit operation systems be intensiŽ ed i.e. reactors, heat exchangers, distillation columns, separators etc. Wherever possible the aim should be to develop and use multi-functional modules for performing heat transfer, mass transfer, and separation duties. PI encompasses not only the development of novel, more compact equipment but also the development of intensiŽ ed methods of processing such as the use of ultrasonic and radiation as energy sources. Additional beneŽ ts of PI are improved intrinsic safety, easier scale up, and increased energy efŽ ciency. Adopting the PI approach can substantially improve the intrinsic safety of a process by having a signiŽ cantly reduced volume of potentially hazardous chemical at any time in a smaller intensiŽ ed unit. In addition, one of the objectives of PI is to move away from batch processing to small continuous reactors, the latter giving more efŽ cient overall operation especially in the case of hugely exothermic reactions whereby the heat can be removed continuously as it is being released. The inherent safety aspect of PI based technologies and its role in minimizing hazards in the Chemical and Process Industries has been discussed in a recent article. Design considerations which may be taken into account for intensifying a process are presented in Table 1.