CHE 412 Process Dynamics and Control BSc Engg
CHE 412 Process Dynamics and Control BSc (Engg) Chemical Engineering (7 th Semester) Week 3 (contd. ) Mathematical Modeling (Contd. ) Luyben (1996) Chapter 3 Stephanopoulos (1984) Chapter 5 Dr Waheed Afzal Associate Professor of Chemical Engineering Institute of Chemical Engineering and Technology University of the Punjab, Lahore wa. icet@pu. edu. pk 1
Modeling CSTRs in Series constant holdup, isothermal • F 0 V 1 K 1 T 1 Luyben (1996) F 1 CA 1 V 2 K 2 T 2 F 2 CA 2 V 3 K 3 T 3 F 3 CA 3 2
Modeling CSTRs in Series constant holdup, isothermal • 3
Modeling CSTRs in Series constant holdup, isothermal • 4
Modeling CSTRs in Series Variable Holdups, nth order • Changes from previous case: V of reactors (and F) varies with time, reaction is nth order Parameters to be known: k 1, k 2, k 3, n Disturbances to be specified: CA 0, F 0 Unknown variables: CA 1, CA 2, CA 3, V 1, V 2, V 3, F 1, F 2, F 3 CV Include MV Controller eqns V 1 (or h 1) F 1 = f(V 1) V 2 (or h 2) F 2 = f(V 2) V 3 (or h 3) F 3 = f(V 3) 5
Modeling a Mixing Process Basis and Assumptions F (volumetric), CA (molar); Well Stirred Stephanopoulos (1984) Feed (1, 2) consists of components A and B Enthalpy of mixing is significant Process includes heating/ cooling H H ρ is constant 2 1 Q in or out H 3 6
Modeling a Mixing Process H 2 H 1 H 3 7
Modeling a Mixing Process Put values of h in overall energy balance 8
Modeling a Mixing Process 9
Tips For Assessment (Exam) Introduction + Modeling (week 1 -3) In exam, you may be asked short descriptive questions to check your understanding of process control and to prepare a mathematical model for a chemical process or processes and to make the system exactly specified (i. e. Nf = 0) 1. Consult your class notes, board proofs, discussions 2. Stephanopoulos (1984) chapters 1 -5, examples and end-chapter problems 3. Luyben (1996) chapter 3 page 40 to 74. Practice examples and end-chapter problems for chapter 3. 10
Week 3 Weekly Take-Home Assignment 1. Follow all the example modeling exercises in Luyben (1996) chapter 3 page 40 to 74. Practice these example processes. 2. Solve at least 10 end-chapter problems from Luyben (1996) chapter 3 (Compulsory) Submit before Friday (Feb 7) Curriculum and handouts are posted at: http: //faculty. waheed-afzal 1. pu. edu. pk/ 11
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