Constant-Density CSTR

This will be the most used forni of the mass-balance equation in the CSTR in this book. Students should either memorize this equation or preferably be able to derive it from an integral mass balance on the reactor. This equation requires three major assumptions  

For a reactant species A (va = — 1) the steady-state mass balance becomes 

For first-order kinetics, n = 1, the mass balance becomes 

Note that we simply had to solve an algebraic equation to find Ca ( ) or T (CA). 

In a CSTR with any single reaction rate r(CA), we can always solve explicitly for X as 

---

Suppose the following reaction network is occurring in a constant-density CSTR ... 

Solution The component balance for component A (styrene) for a first-order reaction in a constant-volume, constant-density CSTR is... 

Example 14.6 Explore the consequences of the following shutdown strategy for an isothermal, constant-density CSTR that has been operating at steady state. At time zero, the discharge flow rate is increased by a factor of 1 -b 5. Simultaneously, the inlet flow rate is made proportional to the fluid volume in the vessel. When does the vessel empty and what happens to the composition of the discharge stream during the shutdown interval ... 

Ideal Continuous Stirred Tank Reactor In an ideal CSTR, reactants are fed into and removed from an ideally mixed tank. As a result, the concentration within the tank is uniform and identical to the concentration of the effluent. The mass and energy conservation equations for an ideal constant-volume or constant-density CSTR with constant volumetric feed rate V may be written as... 

Table 7-2 and Figs. 7-3 and 7-4 show the analytical solution of the integrals for two simple first-order reaction systems in an isothermal constant-volume batch reactor or plug flow reactor. Table 7-3 shows the analytical solution for the same reaction systems in an isothermal constant-density CSTR. 

Suppose the reactor is run in a constant-density CSTR with 0 = 15 mol m , =... 

The simplest case is when the experiments are performed in a constant-density CSTR. Then the measured inlet and outlet concentration give the reaction rate directly ... 

Again, we could have obtained this equation by starting with the design equation for a constant-density CSTR (Eqn. (3-24)), applying it to species B, and recognizing that rfe = 1 Ca — 2Cr. 

---