Multiple Reactions in a CSTR

For a CSTR. a coupled set of algebraic equations analogous to PFR differential equaiion.s must be solved. 

Recall that in Equation (6-I7J is a function ) of the species con trations 

After writing a mole balance on each species in the reaction set. we siibsti for concentrations in the respective rate laws. If there is no volume cht with reaction, we use concentrations., as variables. If the reactions are phase and there is volume change, we use molar How rates.. as variat The total molar flow rate for n species is 

For q reactions occurring in the gas phase, where N different species present, we have the following set of algebraic equations  

We can use an equation solver in Polymath or a similar program to sc Equations (6-31) through (6-33). 

For a CSTR. a coupled set of algebraic equations analogous to the PFR differential equations must be solved. These equations are arrived at from a mole balance on CSTR for every species coupled with the rates step and stoichiometry. For q liquid phase reactions occurring where N different species are present, we have the following set of algebraic equations  

We can use a non-linear algebraic equation solver (NLE) in Polymath or similar program to solve Equations (8-17) through (8-19). 

Example ft-6 Complex Reactions in a Liquid Phase CSTR 

The complex reactions discussed in Example 8-5 now take place in the liquid plwse in a 2,500 dm- CSTR. The feed is equimolar in A and B with F = 200 mol/min and the volumetric flow rate is 100 dm-Vmin. The rate consuutis are 

Find the comentrations of A. B, C. and D exiling the reactor, along with the exiling selectivity. 5od- 

---

I m not talidng about fun you can have at an amusement park, but CRE fun. Now that we have an understanding on how to solve for the exit concentrations of multiple reactions in a CSTR and how to plot the species concentration down the length of a PER or PER, we can address one of the most important and fun areas of chemical reaction engineering. This area, discussed in Section 6.1, is learning how to maximize the desired product and minimize the undesired product. It is this area that can make or break a chemical process financially. It is also an area that requires creativity in designing the reactor schemes and feed conditions that will maximize profits. Here you can mix and match reactors, feed steams, and side streams as well as vary the ratios of feed concentration in order to maximize or minimize the selectivity of a particular species. Problems of this type are what I call digital-age problems - because... 

Example S tl Multiple Reactions in a CSTR The elementary liquid-phase reactions... 

Ettample 8-11 Multiple Reactions in a CSTR 08-i3-2tXM. RcvS i.232 Ode Report (RKF4S)... 

Example H-5 Piwluetion of Ac etic Anhydride Example 8-9 CSTR with CooUna Coil Example H-IO Parallel Reaction in a PER with Heat Effects Example H-H Multiple Reactions in a CSTR... 

---