Elements of
Chemical Reaction Engineering
6th Edition



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Essentials of
Chemical Reaction Engineering
Second Edition

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Chapter 12: Steady-State Nonisothermal Reactor Design: Flow Reactors with Heat Exchange

Example - Using N/S vs. S Plot

The elementary gas phase reaction

                                                                 

is to be carried out in a PFR with external cooling. The entering pressure is 24.6 atm and the entering temperature is 227°C. The feed is 66.7% A and 33.3% inert. The ambient temperature in the heat exchange is constant at 500K. What is the largest tube diameter one can have and not have runaway.

 

Additional Information

                                                    

                                       

Hint 1 - Calculate S

Hint 2 - Calculate N

Hint 3 - Find N/S for = 50

Hint 4 - Calculate dt

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hint 1 Calculate S

    

                                             

at T = T0

                                                        

                            

               

           

Back to problem

 

 

 

 

 

 

 

 

 

 

 

 

 

Hint 2 - Calculate N

                                           

                                                        

                                 

                                                       

                                     

                  

                                                             

Back to problem

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hint 3 - Find N/S for = 50

For S = 50 and a 2nd order reaction (n=2) We find from Figure on the web  = 1.6

Back to problem

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hint 4 - Calculate dt

                                            

                                                   

                                                           

                                              One could have calculated the ratio.

                                                   One could have calculated the ratio.

                                     

                                                without calculating N separately.

Back to problem 

 

Back to Runaway Reactions in PFRs