16 Residence Time Distributions of Chemical Reactors Chapter 16
Fogler_Ch16.fm Page 1 Tuesday, March 14, 2017 6:24 PM Residence Time 16 Distributions of Chemical Reactors Nothing in life is to be feared. It is only to be understood. —Marie Curie Overview. In this chapter we learn about nonideal reactors; that is, reactors that do not follow the models we have developed for ideal CSTRs, PFRs, and PBRs. After studying this chapter the reader will be able to describe: • General Considerations. How the residence time distribution (RTD) can be used (Section 16.1). • Measurement of the RTD. How to calculate the concentration curve (i.e., the C-curve) and residence time distribution curve, (i.e., the E-curve (Section 16.2)). • Characteristics of the RTD. How to calculate and use the cumula- tive RTD function, F(t), the mean residence time, tm, and the vari- ance σ2 (Section 16.3). σ2 • The RTD in ideal reactors. How to evaluate E(t), F(t), tm, and for ideal PFRs, CSTRs, and laminar flow reactors (LFRs) so that we have a reference point as to how much our real (i.e., nonideal) reac- tor deviates form an ideal reactor (Section 16.4). • How to diagnose problems with real reactors by comparing tm, E(t), and F(t) with ideal reactors. This comparison will help to diagnose and troubleshoot by-passing and dead volume problems in real reactors (Section 16.5). 16.1 General Considerations The reactors treated in the book thus far—the perfectly mixed batch, the plug-flow tubular, the packed bed, and the perfectly mixed continuous tank reactors—have been modeled as ideal reactors.
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