Process Integration of Organic Rankine Cycle for Waste Heat Recovery in Industry Process and Optimization

本研究主旨在於探討有機朗肯循環(Organic Rankine Cycle)用於工業程序中廢熱回收的問題與最適化，並提出一套數學規劃法用於與 有機朗肯循環整合後的熱交換器網路。 起初參考Yee and Grossmann(1990a,1990b)所提出之熱交換網路階層超結構，本文提出一整合熱交換器網路與有機朗肯循環的超結構，此超結構涵括了 熱交換器網路裡各程序流與有機朗肯循環可能發生的熱交換配對情形。根據此超結構以及各階層中發生的物理現象，我們可以將其建立 一個混合整數非線性規劃(MINLP)的數學模型(model)，此模型與超結構都可以包含各種可能的情形。 在本論文中針對此熱交換器網路問題，分成兩個主要的步驟進行求解：(1)在未使用有機朗肯循環之前，合成具最少能源使 用量之熱交換器網路；(2)基於步驟(1)所得的結果，將步驟(1)在狹點(pinch point)以上的結構固定，而在狹點以下使用有機朗肯循環 回收程序中仍未被善加利用的廢熱，並以最大化淨輸出功為目標函數，得到一新的熱交換器網路。透過例子進行討論與分析， 驗證提出的超結構與數學模型，並找出最適合的各參數，合成出最佳化的 有機朗肯循環工業程序廢熱回收系統。This thesis aims at developing a mathematical model for the synthesis of a heat exchanger network which can be integrated with the organic rankine cycle (ORC) for recovery of low-grade waste heat. An integrated stagewise superstructure, which is analogous to the superstructure introduced by Yee and Grossmann for the synthesis of heat exchanger networks, is proposed for including the ORC as part of the heat recovery system. The integrated stagewise superstructure can represent all possible interconnections and interactions between process streams and the ORC. Based on this superstructure, the synthesis of heat exchanger networks with the ORC streams is formulated as a mixed-integer nonlinear program (MINLP). %Not using any heuristics that are based on the concept of pinch points, the proposed superstructure for the synthesis %of heat exchange networks is formulated as a MINLP optimization model. A two-steps solution method is suggested to solve the MINLP problem: (1) A heat exchanger network excluding the ORC is solved for minimizing the utility consumption; (2) Based on the results of step one, a modified network including the ORC below the pinch point is synthesized for maximizing the generated work from the ORC turbine. Numerical examples from the literature are supplied to demonstrate the applicability the the proposed approach, and discussion and analysis can help finding the best scenario on waste heat recovery.Thanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i ChineseA.b.str.ac. t. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v List of Fig. u.re.s. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix List of Ta.bl.es. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi 1 Introduction 1 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Introduction to Heat Exchanger Networks . . . . . . . . . . . . . . . . . . 2 1.3 Introduction to ORC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.4 LiteratureSurvey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.5 Motivation andObjective . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.6 Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2 ReviewofHENS 11 2.1 Illustration ofModeling . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2 HENSAssumption andModeling . . . . . . . . . . . . . . . . . . . . . . 12 2.3 Illustration of aGenericSuperstructure . . . . . . . . . . . . . . . . . . . 16 2.4 Indices,Sets,Parameter, andVariables . . . . . . . . . . . . . . . . . . . 18 2.5 Contraints andObjectiveFunction . . . . . . . . . . . . . . . . . . . . . 20 2.5.1 Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.5.2 ObjectiveFunction . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.6 Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3 Supertructure and Formulation for ORC-integrated HENS 27 3.1 Illustration ofModeling . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.2 Assumption forModeling . . . . . . . . . . . . . . . . . . . . . . . . . . 28 3.3 Indices,Sets,Parameter, andVariables . . . . . . . . . . . . . . . . . . . 30 3.4 ObjectiveFunction andContraints . . . . . . . . . . . . . . . . . . . . . . 35 3.4.1 Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.4.2 ObjectiveFunction . . . . . . . . . . . . . . . . . . . . . . . . . . 46 3.5 Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4 Optimization and Discussion 51 4.1 optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 4.2 Comparison betweenDifferentWorkingMediums . . . . . . . . . . . . . 60 4.3 Economic Estimate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 5 Conclusions and Future Works 73 5.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 5.2 FutureWorks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Reference. s.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8