KING FAHD UNIVERSITY CHEMICAL ENGINEERING COURSE NOTES (Process Control)-Lec26

KING FAHD UNIVERSITY CHEMICAL ENGINEERING COURSE NOTES (Process Control)-Lec26

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Unformatted text preview: 1 Chapter 11 1. Summer 2. Comparator 3. Block Blocks in Series are equivalent to... G(s)X(s) Y(s) = Chapter 11 2 Chapter 11 Figure 11.10 Three blocks in series. Figure 11.11 Equivalent block diagram. 3 Chapter 11 Block Diagram Reduction In deriving closed-loop transfer functions, it is often convenient to combine several blocks into a single block. For example, consider the three blocks in series in Fig. 11.10. The block diagram indicates the following relations: 1 1 2 2 1 3 3 2 (11-11) X G U X G X X G X = = = By successive substitution, 3 3 2 1 (11-12) X G G G U = or 3 (11-13) X GU = where 3 2 1 . G G G G @ 4 Chapter 11 Figure 11.8 Standard block diagram of a feedback control system. 5 Chapter 11 Closed-Loop Transfer Functions The block diagrams considered so far have been specifically developed for the stirred-tank blending system. The more general block diagram in Fig. 11.8 contains the standard notation: Y = controlled variable U = manipulated variable D = disturbance variable (also referred to as load variable) P = controller output E = error signal Y m = measured value of Y Y sp = set point internal set point (used by the controller) sp Y = % 6 Chapter 11 Y u = change in Y due to U Y d = change in Y due to D G c = controller transfer function G v = transfer function for final control element (including K IP , if required) G p = process transfer function...
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This note was uploaded on 09/22/2009 for the course CHEMICAL CHE 401 taught by Professor Dr.muhammadal-arfaj during the Spring '09 term at King Fahd University of Petroleum & Minerals.

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KING FAHD UNIVERSITY CHEMICAL ENGINEERING COURSE NOTES (Process Control)-Lec26

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