123 Applications To Reactor Engineering

General issues in reactor engineering are discussed in Chapter 1. Many of these issues are also discussed in Chapters 10 and 11 with reference to stirred tank and bubble column reactor. These discussions are also applicable to the engineering of fluidized bed reactors. As mentioned repeatedly in this book, it is first necessary to evolve a 'wish list' for the reactor to quantify demands on the reactor. Suitable reactor configurations and modes of operation can then be evolved. Krishna (1994) discussed a systematic approach for the selection of appropriate reactor and mode of operation. Available modeling tools can then be used to short-list the most promising configurations. Classical reaction engineering models give useful information about the overall behavior of the reactors. Usually two-phase or three-phase models are used to simulate bubbling fluidized bed reactors (Kunii and Levenspiel, 1991). These models are also extended to simulate turbulent beds. Grace et al. (1999) developed a generalized bubbling turbulent (GBT) bed model based on a probabilistic approach. Usually plug flow is assumed to simulate the behavior of riser reactors. An approach analogous to GBT can also be developed for the fast-fluidization regime in riser



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