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Chapter 1

Chapter 1. Essentials ( 精華 ; 基本要素 ). Control. Manual Control ( 手動控制 ) Automatic Process Control ( 自動程序控制 ) Sensor ( 感測器 ) Transmitter( 傳送器 ) Controller( 控制器 ) Final Control Element ( 最後控制元件 ; 最後控制機構 ). Heat Exchanger Control Loop.

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Chapter 1

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  1. Chapter 1 Essentials (精華 ; 基本要素)

  2. Control • Manual Control (手動控制) • Automatic Process Control (自動程序控制) Sensor (感測器) Transmitter(傳送器) Controller(控制器) Final Control Element (最後控制元件; 最後控制機構)

  3. Heat Exchanger Control Loop • TC: Temperature Controller • TT: Temperature Transmitter

  4. Feedback Control Systems (回饋控制系統、回授控制系統) • Basic Components: 1. Sensor-Transmitter 2. Controller 3. Final Control Element • These operations are: 1. Measurement (M) 量測 2. Decision (D) 決策 3. Action (A) 行動

  5. Control Valve (Final Control Element)

  6. Terms of Automatic Process Control • Controlled Variable (受控變數) or Process Variable (程序變數) • Set Point (SP) 設定點 • Controller Output (CO) • Manipulated Variable (操縱變數) • Disturbance (干擾) or Upset (攪亂) • Closed-Loop Control = Feedback Control

  7. Block Diagram of aFeedback Control System

  8. The Objective of Automatic Process Control • The objective of an automatic process control system is to adjust the manipulated variables to maintain the controlled variables at its set point in spite of disturbances.

  9. The Important of Automatic Process Control • Prevent injury to plant personnel, protect the environment by preventing emissions and minimizing waste, and prevent damage to the process equipment. • Maintain product quality on a continuous basis and with minimum cost. • Maintain plant production rate at minimum cost.

  10. Transmission Signals (傳輸訊號) • Pneumatic Signal (氣動訊號): 3 ～ 15 psig or 0.2～1.0 kg/cm2 gauge. • Electrical Signal: 4 ～ 20 mA Less often 10 ～ 50 mA, 1 ～ 5 V, or 0 ～ 10 V are used. • Digital or Discrete Signal: (數位訊號; 離散訊號)

  11. Transducer (變換器; 換能器) or Converter (轉換器) • To change one type of signal into another. • I/P transducer: current (I) to pneumatic (P) • Other type of transducers: digital-to-analogy: D to A converter pneumatic-to-current: P/I transducer voltage-to-pneumatic: E/P transducer pneumatic-to-voltage: P/E transducer

  12. Control Strategies (控制策略) • Feedback Control (回饋控制) • Feedforward Control (前饋控制)

  13. Feedback Control System

  14. Feedback Control System

  15. Regulatory and Servo Control • Regulator Control (調節控制) ☆ No change in set point ☆ Disturbances may change • Servo Control (伺服控制) ☆ Servo = servomechanism (伺服機構) ☆ Set point may be changed as a function of time (say, batch reactor control).

  16. Feedforward (前饋) Control System

  17. Feedforward Control with Feedback Compensation (補償)

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