外文中英文翻译机电工程过程装备专业精馏塔的设计适用于毕业论文外文中英文翻译+中英文对照.DOC

－ PAGE II － - PAGE 12 - ABSTRACT Steady?state?models?continue?to?be?powerful?and?efficient?tools?for?designing?control?systems? for?distillation?columns.??This?paper?presents?a?control?design?procedure?and?an?example? applicati n?of?this?technique?to?an?actual?column. KEYWORDS Computer?Aided?Engineering,?Simulated?Distillation,?Chemical?Processing,?Distillation?Control,?Steady?State?Modeling??? INTRODUCTION ： Steady state process models have long been used to assist the control engineer in designing control strategies for distillation columns. However, with the large number of industrial columns still operating in manual or with ineffectual controls, there remains a need for sound distillation column control design techniques. We believe that Tolliver and McCune (1978) have made the greatest contribution to the development of this type of design procedure. Two other very good papers on this subject are by Thurston (1981) and Roat, et al (1988). While our procedure is an extension of that proposed by Tolliver and McCune, we have improved the procedure in the following ways · We advocate that mass flows be used in models versus the previous standard of molar flows. We have determined independently that use of molar flows can lead to incorrect results. A recent review article on distillation column control by Skogestad (1992) confirms these findings. · We also advocate that the actual control structure be enforced when using the steady state simulation to identify a temperature sensor location for composition control. This is accomplished by a careful choice of independent variables when defining the model solution conditions. Tolliver and McCune advocate varying only molar distillate flow regardless of the proposed control structure. This too can lead to incorrect results. · We show that this technique can be used for multicomponent columns to quantify the incremental benefit of composition control using on-line analyzers versus temperature co