Dynamics of Reactor-Stripper Process

In Chapter 2 (Section 2.9.2) the steady-state design of a reactor-stripper process was studied. Now we investigate the dynamic controllability of this process. The dynamic model of the reactor is the same as Eqs. (3.9)—(3.11) except there is a second stream entering the reactor, the recycle stream D (kmol/s) from the column with composition. Vj) (mole fraction A). The reactor effluent is F (kmol/s) with composition z (mole fraction A). The reactor component and energy balances are  

The dynamic model of the stripping column consists of one ordinary differential equation per tray if equimolal overflow, constant liquid holdups on the trays, and instantaneous 

Vapor-liquid phase equilibrium is assumed on each tray, so the vapor composition can be calculated from the known relative volatility a = 1.5 and liquid composition  

The molar holdup in the base of the column is MP and in the overhead accumulator is Mn. These holdups are not constant but vary with time. The total molar and component balances for the base and reflux drum are given below  

Remember that the stripping column has no reflux. These levels are controlled by proportional level controllers that manipulate P and D. Tray holdup is 0.3 kmol, and the steady-state holdups in the base and overhead accumulator are each 75 kmol. 

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