• 作者： Hsu, Tsong-Fuh; Yu, Cheng-Ching; Liou, Ching-Tien
• 中文摘要： 高純度蒸餾塔是一高度的非線性系統,使用傳統的單一溫度控制或直接濃度控制,很難得到良好的產品成份控制。本研究嘗試利用準確的線上色層分析儀和快速動態響應溫度量測器的相互配合來執行高純度蒸餾系統的產品成份控制。根據此一原則,一個理想的高純度蒸餾系統的產品成份控制基本上應包括三個問題:(1)控制結構的選擇,(2)溫度量測位置的選擇,(3)控制器的設計。首先我們選擇傳統的溫度/濃度並聯串級控制為控制結構。雖然結構上十分傳統,但是我們採用一個新的設計哲學。基本上是將次要環路溫度控制器設計成一個消除干擾的前饋控制器,再加上回饋的濃度控制器,來維持產品成分。本論文提供了一個有系統的方法來設計溫度/濃度並聯串級控制,其中包括利用相互作用量測值(.gamma.)來作為次要溫度量測位置的選擇以及溫度控制器的設計。然後從ATV方法找出主要環路控制器設計所依據之轉移函數而得到主要環路控制器之參數。最後用一個多成份蒸餾系統來控制塔頂濃度(不純度400 ppm)為例、比較了三種不同控制結構:1.單一溫度回饋控制,2.直接濃度控制, 3.溫度/濃度並聯串級控制。模擬結果顯示並聯串級控制,利用次要環路溫度控制器的快速響應使產品成份仍維持在線性區域,加上主要環路成份控制器的準確性,能使產品成份達到要求規格。
• 英文摘要： The strong non-linearity of high-purity distillation columns makes the composition control difficult. Conventional single temperature control or direct composition control often performs poorly. Effective composition control can be achieved by the combination of accurate on-line composition analyzer and fast temperature measurement. Taking this approach, three questions need to be addressed: (1) the selection of a proper control structure,(2) the selection of temperature measurement locations and(3) the design of controllers. In this work, the temperature/composition cascade control structure is used throughout. Under the familiar control structure a new design philosophy is employed. Using the parallel cascade control structure, the temperature controller acts as a feedforward controller to overcome load disturbances and the feedback composition controller is designed to maintain product quality under the uncertainty of the feedforward gain. The temperature measurement location is selected such that the feedforward gains are close to each other for load disturbances of interest. The interaction measure (.gamma.) serves as a criterion for the selection of temperature measurement location. The temperature controller is also designed according to .gamma.. Finally, the autotune variation (ATV) method is used to design the composition controller according to the linear model identified. The design procedure is applied to a high-purity (400ppm) BTX distillation column. Simulation results show that the proposed method gives a much better composition control over conventional composition control techniques.
• 中文關鍵字： 蒸餾控制; 並聯串級控制; 前饋控制; 組成控制
• 英文關鍵字： Distillation; Parallel Cascade Control; Feedforward Control; Composition Control