| Summary: | 博士 === 國立臺灣大學 === 化學工程學研究所 === 94 === This dissertation deals with the synthesis and retrofit problems of mass exchange networks (MENs) by adopting a mathematical programming approach based on the stage-wise superstructure representation of the MENs. It is analogous to the one introduced by Yee and Grossmann (1990a,1990b) for synthesis of heat exchange networks (HENs). This stage-wise superstructure-based representation can not only handle multiple transferable components and reactive separating agents directly, but also be extended to include regeneration networks straightforwardly. Not using any heuristics that are based on the concept of pinch points, the proposed superstructure-based representation for MEN''s is formulated as a mixed-integer nonlinear programming (MINLP)
optimization model. Therefore, any objects can be minimized simultaneously.
Also, two novel strategies for the synthesis of cost effective flexible heat/mass exchanger networks that involves specified uncertainties in the source-stream temperatures/compositions and flow rates is presented. The first strategy is active set strategy that is decomposed into three main iterative steps: (1) the simultaneous HEN or MEN synthesis to attain a network configuration with a minimum total annual cost (TAC); (2) the flexibility analysis to test whether the network obtained from the synthesis step is feasible or not in the full disturbance range; and (3) the integer cuts to exclude disqualified network configurations. The second strategy is random simulation that is also decomposed into three main steps:
(1) the simultaneous HEN or MEN synthesis to attain a network configuration with a minimum total annual cost (TAC); (2) flexibility test without consideration of the size restrictions to verify whether the current network candidate is feasible or not for a large number of corrected uncertain parameters; and (3) with consideration of the size restrictions that have been ignored previously, execution of flexibility test of the network qualified in step (2), with an increase of the size of individual exchange units if necessary. A few iterations of these three steps for the two strategies are required to secure the desirable results.
In addition, a multi-criteria synthesis strategy for heat-exchanger networks (HENs) simultaneously considering minimum utility consumption, maximum source-stream temperature flexibility, and even minimum number of matches is also proposed. The flexible HEN synthesis problem is formulated as a multi-objective mixed-integer linear programming (MO-MILP). For handling the multiple conflict design targets, a two-phase fuzzy multi-criteria decision-making method is presented to attain a best compromised solution.
Final, several examples from literatures are supplied to demonstrate the applicability of the proposed MENs synthesis and retrofit models and the efficiency of the proposed strategies.
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