Created at Universidad de Guanajuato & École Polytechnique de Montréal

1. Program for North American Mobility in Higher Education (NAMP) Introducing Process Integration for Environmental Control in Engineering Curricula (PIECE) Module 15: Process Control and Process Integration – Tier 2 Created at Universidad de Guanajuato & École Polytechnique de Montréal

2. This module is divided in three essentials complements, it will demonstrate the relationship between the use of PI tools in order to design a process and the control strategies.

3. Structure • Tier one: • Basic Concepts About Process Control • Tier Two: • Use of PI tools and especially dynamic simulation to address control strategies • Tier Three: • Analysis of a real process.

4. Index: • Tier one: • Comparison between Steady Sate and Dynamic State. • Important Definitions about dynamic state. • Dynamic Models.

5. Index: • Tier two: • Relationship between Process Design and Process Control • Dynamic Effect on recycle Structures.

6. Tier 2

7. Tier 2 Objective: • Understand the interaction between process design and process control. • Understand the effect of recycle structures on dynamic behavior.

8. Process Control in a Integrated Perspective

9. Any process starts with Identification and creation of potential opportunities to satisfy societal needs and to generate profit.

10. Manufacturing process Natural Resources Basic Chemical products Basic Chemical products Manufacturing process Industrial Products Basic Chemicals industrial Products Manufacturing process Consumer Products

11. The next step is Process Creation

12. Process design starts with the synthesis of a process to convert raw material into desired products Product Streams Feed Streams ?

13. Process Flowsheet Is a diagrammatic representation of the process steps using icons to represent process units and arrows to represent connections among them Product Streams Feed Streams

14. It is common the presence of recycles (process integration) because its advantages to recover energy. However is important to know how they affect the dynamic properties. Simulation Steady State

15. Simulation Is a mathematical model of the process that attempts to predict how the process would behave if it were constructed or modified Product Feed New Operating Condition Operating Condition Steady SateSimulationthe operating conditions are changed to others ones in order to evaluate new operating sceneries

16. Having the process flowsheet the next step is to evaluate the process control configuration. • How to control the process. • Effect of the recycle in process dynamic • Effect of the heat integration in process dynamic. Dynamic StateSimulation allows to test different control strategies and to know the influence of changes in the process design on the dynamic behavior.

17. The role of Control Process in Process Design

18. Effect of recycle

19. Recycle Structures These structures are used often in process plants to return material for reprocessing and to recover energy from effluent streams trough heat exchanger.

20. Fresh feed is heating using the stream leaving the reactor Heat Recycle This stream goes trough a heat exchanger in order to recover heat

21. T0(s) TR(s) T1(s) Tf(s) + GH1(s) GR(s) T2(s) GH2(s) Block diagram for this system

22. Now using block diagram algebra to determine el behavior of the integrated system transfer function is: Characteristic Equation Poles of overall system are different to the poles of the individual units. The stability of this system cannot be guaranteed even if each individual system is stable. Block Diagram

23. Without Recycle With Recycle Now defining Gain Time Constant

24. Time constant and gain have been increased in the reactor with recycle Performing a Dynamic Simulation to know the dynamic behavior

25. 500 500 100

26. Why ? Increase in T0 Affects Tf Affects TR The output is reinforced through the recycle exchanger There is a positive feedback

27. According the previous slides • The time constant and the steady state gain of the overall system with recycle can be changed substantially from their values without recycle. • Recycle can alter the stability and possibility for a periodic behavior of the overall system, because it affects the poles of the overall system. • This effect should be considered when the process control is developed because the time constant is related with the speed of response of the process.

28. QUIZ

29. 1.- The effect of a positive feedback is not desirable because : a) Its actions tends to increase the error from desired. b) Its action tends to reduce the error from desired.

30. 2.- If time constant increases its value , it implies : a) A slow system´s response when changes on manipulated variables are made to produce changes on controllable variable. b) A faster system´s response when changes on manipulated variables are made to produce changes on controllable variable.

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35. CONGRATULATIONS! Now you have finished Tier 2