隔牆式蒸餾塔之高等控制策略研究

The Study of the Model Predictive Control Strategy on the Dividing-Wall Distillation Column

江世澤(Shr-Tze Jiang) ； 柯經緯(Jing-Wei Ke) ； 陳萬容(Wan-Rung Chan) ； 許倖嘉(Shing-Jia Shiu) ； 蔡銘璋(Ming-Jang Tsai) ； 洪正宗(Jeng-Tzung Hung)

《石油季刊》 41卷3期 (2005/09) Pp. 1-11

https://doi.org/10.30128/JP.200509.0001

摘要

具有側流之蒸餾塔，側流產品之沸點係介於塔頂產品與塔底產品之間，但有時候側流位置太接近進料板，側流產品會受進料干擾，因此必須使用兩支蒸餾塔才能達到分離之目的，隔牆式蒸餾塔(Dividing-Wall Column)係將一塊隔板置於蒸餾塔中間某一段位置，將進料與側流隔開，側流產品不會直接受進料干擾。隔牆式蒸餾塔可以比傳統使用兩支蒸餾塔節省30%能源與30%設備費用，但塔盤設計與操作困難度較高。本文之目的在於探討隔牆式蒸餾塔之控制策略，本文採用模式預測性控制(Model Predictive Control, MPC)方法應用在隔牆式蒸餾塔之操作，利用蒸餾塔三個不同位置之溫度同時控制塔頂產品、側流產品與塔底產品之組成，屬於3×3之多變數控制系統。為了測試模式預測性控制的控制性能，利用實驗室小型隔牆式蒸餾塔進行測試。測試結果顯示控制性能尚佳，但受限人力，無法進行長時期之連續操作。隔牆式蒸餾塔隔牆兩邊之內回流流量會影響操作，本文進行之實驗，內回流係由內回流泵來控制，隔牆兩邊之內回流流量分別由閥控制兩邊之流量相同，未來將繼續進行隔牆兩邊之內回流流量控制之多變數控制研究。

關鍵字

蒸餾 ； 隔牆塔 ； 模式預測性控制

並列摘要

The boiling point of the side stream of a continuous distillation column is between that of the top and bottom products. Due to the closeness of the position to the feed, the quality of the side stream is easily disturbed by variations in the feed stream. This leads to a two-column system to be used for the separation. Therefore, putting a dividing wall in certain section of a column to separate the feed and side stream, the quality of the side stream will not be disturbed by the feed. The energy consumption and the equipment cost of the dividing-wall column would be 30% lower than those of the two-column system. However, the difficulty in tray design and the complexity in the operation of a dividing-wall column limit its application. This paper will discuss the control strategy of the dividing-wall column. To testing the performance of the control system, a lab-scale dividing-wall distillation column was constructed. Applying the Model Predictive Control technique to the dividing-wall column, the qualities of the both top and bottom as well as the side stream products were controlled by using a 3×3 multivariable process for the column temperature at three different positions. The experimental results demonstrate a good performance for applying model predictive control technique to the dividing-wall column. However, the long time continuous operation was not tested due to the limitation of the manpower. The reflux rate was controlled by a metering- pump. The ratio of internal flow rate in both side of the dividing-wall was controlled by the two How-controllers. In this study, internal flow rates in both side of the dividing-wall were the same. The column performance will be influenced by the internal flow rates in the both side of the dividing-wall. A study of this ratio to the controllability of the multivariable control system will be performed in the future.

並列關鍵字

Distillation ； Dividing-Wall Column ； Model Predictive Control