Abstract:

In view of the retrofit of heat exchange network (HEN), a retrofit idea of using utility heat to realize the concept of multi-energy complementation is proposed, which means by fully utilizing low temperature waste heat in the thermal process fluid, the retrofit of heat integration system is completed. This paper is based on the reference point non-dominated sorting genetic algorithm (NSGA-Ⅲ), through comprehensive evaluation of annual retrofit cost, annual retrofit profit, energy consumption (including heat exchange network cooling / heating utilities and waste heat system cooling water and power consumption) and beneficial output of waste heat systems of the heat integrated system considering waste heat recovery (WHR), so as to obtain optimal solution. In the case study, the retrofit of crude oil distillation system (10H5C) shows that by weighing the four goals of energy consumption, output of the WHR system, retrofit cost and retrofit profit of the integrated system, NSGA-Ⅲ algorithm is used to solve the multi-dimensional retrofit plan. Compared to basic network, it not only can provide users with a retrofit plan that saves a maximum of 22.9% of energy consumption, but also can provide a solution with a maximum output of WHR system of 4.003×10⁴kW, and can also provide a minimum retrofit. It can also develop a retrofit plan with a minimum retrofit cost of 1.848×10⁶USD/a, as well as a solution with a maximum retrofit profit and a minimum return on investment of 1.173×10⁷USD/a and 121%, respectively. Finally, by comparing retrofit performance of the integrated WHR system with HEN alone, the practicability and feasibility of the integrated WHR system, and the important role of waste heat recovery multi-energy complementary technology in improving the energy utilization efficiency of process industry energy integration system are demonstrated.

Key words: heat exchange network, waste heat recovery, multi-objective optimization, multi-energy complementation, non-dominated sorting genetic algorithm (NSGA-Ⅲ)

摘要：

针对换热网络（HEN）的优化改造，提出了一种利用公用热量实现多能互补理念的改造思路，通过充分利用热过程物流中的低温余热，完成热集成系统的优化改造。本文基于参考点非支配排序遗传算法（NSGA-Ⅲ），通过综合评估集成废热回收（WHR）系统的换热网络的年度改造费用、年度改造收益、能耗（包含换热网络的冷/热公用工程和废热系统冷却水和电力消耗）和废热系统的有益产出，从而获得最优解决方案。对原油蒸馏系统（10H5C）的优化改造研究案例表明，通过权衡集成系统的能源消耗、WHR系统的产出、改造费用和改造收益4个目标，采用NSGA-Ⅲ算法求解获得了多维度的改造方案，相较于基础网络不仅有可以为用户最大节省22.9%能源消耗的改造方案，还有WHR系统最大输出为4.003×10⁴kW的解决方案，也有最小改造费用为1.848×10⁶USD/a的改造方案，还有最大改造收益和最大投资回报率分别为1.173×10⁷USD/a和121%的解决方案；最后通过比较集成WHR系统与单独HEN优化改造的性能，证明了集成WHR系统的实用性和可行性，以及余热回收多能互补技术对提高流程工业能量集成系统能量利用效率的重要作用。

关键词: 换热网络, 废热回收, 多目标优化, 多能互补, 非支配排序遗传算法（NSGA-Ⅲ）