REACTORS: IDEALIZED CHEMICAL REACTORS - Biomass as a Sustainable Energy Source for the Future - page 181

Although this chapter serves as a starting point to understand reaction and reactor
design, the reader is referred to any of the references at the end of this chapter to deal
with complex kinetics, multiple reactions, or multiphase systems.

KEY CONCEPTS

Chemical reactors
Plug flow
Perfectly mixed flow
Balances: mass, energy
Residence time distribution
Axial dispersion

SHORT-ANSWER QUESTIONS

6.1 Compare Equation (6.4) with Equation (6.1). What is the relation between con-
version and concentration when ε A =0?

6.2 Compare Equations (6.22) and (6.29). Assuming a first-order reaction and the
same operation conditions, which reactor needs less volume to obtain the same
conversion, the CSTR or the PFR? Why?

6.3 Assume a BR and a PFR with the same residence time. Which one gives a higher
conversion? Why?

6.4 Is it possible to find a steady-state batch reactor?

6.5 Is it possible to find a non-isothermal steady-state continuous stirred tank reactor
and a non-isothermal steady-state plug flow reactor?

6.6 Consider an exothermic reaction carried out in a jacketed batch reactor. The
cooling flow is connected to a feedback control loop programmed to create
the following temperature ramp inside the reactor: T = a t+ b . Is it necessary

to simultaneously solve the energy and the molar balances in the reactor?

6.7 In Example 6.5, the conversion for the plug flow reactor is 0.69, whereas for the
tubular reactor with RTD, it is 0.67. Would it be possible to find the opposite: a
lower conversion in the plug flow reactor?

PROBLEMS

6.1 Repeat the calculations presented in Example 6.4 for a second-order reaction
with respect to component A.

6.2 A scientist carries out a liquid-phase reaction in an isothermal ideal batch
reactor. The conversion of a reactant A is 0.8 in 8 min and 0.9 in 18 min. What
is the kinetic rate expression for this reaction?