以數學規劃法做熱整合用水網路最適化設計之研究

Abstract

本研究針對工廠中需考慮操作溫度的用水網路設計提供了一個數學方法，同時考慮了滿足所有製程用水單元需求的最適化水網路設計，以及最適化的熱交換網路設計。另外，在考慮熱整合的水網路型態上，也將再生再利用和再生再循環利用水網路，兩者不同型態的水網路設計，詳加說明，並利用兩個簡單的例子加以分辨其水網路型態的不同，並加以延伸討論其熱交換網路結構上的不同。而這個以超結構為背景數學模式建構，包含了許多實際操作的限制式，例如供應水流量限制，操作成本，污水處理成本，公用能源成本和年度總成本等等，最後將產生一個混合整數非線性規劃的問題；為了求得最適化水網路具有熱整合設計結構與設計成本考量上的平衡，本研究利用不同的目標函數，提出分段式循序漸近的方法使考慮熱整合的用水網路達到最適化。最後，利用文獻上的一些例子用此方法證明可行並且討論他們的優勢。

In this study, a mathematical programming approach for synthesis of water network with energy integration in chemical plants is developed.This approach considers simultaneously the optimal water networks to satisfy demands of water-using unit and optimal treatment of effluent streams. Concept of regeneration reuse and regeneration recycling water networks with heat integration is explained and distinguished in this method. The superstructure-based mathematical programming approach, which includes many practical operating constraints, flowrate limitations of water supply, operating costs, treatment costs, utility costs, and total annualized cost (TAC), will result in a mixed-integer nonlinear programming problem (MINLP) for synthesis of water network with energy integration. Complex trade-off involving optimal water networks design structure, as well as design costs has been included in this MINLP problem. Therefore, different objections is presented for using sequential design in this study, and there are analytic comparisons between water-using network with heat integration designs for optimal water supply flowrates, optimal utility cost and optimal total annual cost. Furthermore, three water-using processes having different design objectives are used to demonstrate this approach. Finally, some examples from literature are employed to demonstrate the applicability of the proposed strategy and discuss their advantages.