三種類型內隔壁式蒸餾塔之動態控制

Abstract

跟傳統蒸餾塔序列比較之下，內隔壁式蒸餾塔是具有更高的能源效率與更低設備成本的前瞻性設計。然而，因為內隔壁式蒸餾塔是整合型設計，所以設計與控制上較為困難。直到現在，不同類型的內隔壁式蒸餾塔控制與特性仍未被討論過。所以，此研究主要目的是調查與討論三種不同類型隔板式蒸餾塔的控制：上隔板式蒸餾塔(DWCU)、中隔板式蒸餾塔(DWCM)與下隔板式蒸餾塔(DWCL)。使用線性分析工具，相對增益陣列(RGA)與條件數(CN)，來對五種真實多成分系統進行分析。基於分析結果選擇出控制架構進入動態模擬。從動態模擬得到的結果顯示，上隔板式蒸餾塔(DWCU)在這三類型蒸餾塔中控制性最差。下隔板式蒸餾塔(DWCL)在大部分的系統中比中隔板式蒸餾塔(DWCM)具有較高的控制性，但是控制性上的微小差異與其較高的能源消耗使中隔板式蒸餾塔(DWCM)能具有競爭力。在本論文的最後章節中探討三種不同類型隔板式蒸餾塔的溫度控制，結果顯示傳統的溫度控制架構無法給予良好的控制表現。

Compared with conventional distillation columns, the dividing wall column is a promising design with high energy efficiency for separating multi-component mixtures. However, it is more difficult to design and control dividing wall columns because of their integrated designs. Complete study of control of the three types of the columns has never been discussed. Therefore, the main purpose of this work is to investigate the control of three types of dividing wall columns: columns with the dividing wall in the lower (DWCL) middle (DWCM) and upper (DWCU) portions of the column. The relative gain array (RGA) and condition number (CN) for these three column types are calculated for five different multicomponent systems. Based on these results, promising control structures are identified and tested in Aspen Dynamics. The results indicate that DWCU has the worst control performance of the three column types. DWCL outperforms DWCM in most cases, but the difference in controllability is not likely to justify the choice of a column configuration with higher costs. Finally, the temperature control of three types of dividing wall is studied. The results show that conventional temperature control cannot provide good performance in controlling dividing wall columns.