Retrofit of heat exchanger networks with pressure recovery of process streams at sub-ambient conditions
Retrofit of heat exchanger networks with pressure recovery of process streams at sub-ambient conditions
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DOI：
10.1016/j.enconman.2015.02.002
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发表时间：
2015-04
影响因子：
10.4
通讯作者：
V. Onishi;M. Ravagnani;J. Caballero
中科院分区：
文献类型：
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作者：
V. Onishi;M. Ravagnani;J. Caballero
提出了一种新的换热网络改造数学规划模型，其中进行过程流的压力恢复以增强热集成。特别适用于低温过程，HENs改造与联合热和功集成主要旨在减少昂贵的冷服务的使用。建议的多级上部结构允许增加现有的传热面积，以及使用新的设备进行热交换和压力操纵。物流的压力恢复与HEN设计同时进行，因此工艺条件（物流压力和温度）是优化的变量。数学模型采用广义析取规划（GDP）进行了制定，并通过混合整数非线性规划（MINLP）进行了优化，通过最小化改造的总年化成本，考虑到涡轮机和压缩机与辅助电机的耦合。三个案例研究，以评估所开发的方法的准确性，包括一个真实的工业实例相关的液化天然气（LNG）生产。结果表明，蒸汽的压力恢复是有效的节能，因此，为降低HEN改造的总成本，特别是在低于环境的过程。
This paper presents a new mathematical programming model for the retrofit of heat exchanger networks (HENs), wherein the pressure recovery of process streams is conducted to enhance heat integration. Particularly applied to cryogenic processes, HENs retrofit with combined heat and work integration is mainly aimed at reducing the use of expensive cold services. The proposed multi-stage superstructure allows the increment of the existing heat transfer area, as well as the use of new equipment for both heat exchange and pressure manipulation. The pressure recovery of streams is carried out simultaneously with the HEN design, such that the process conditions (streams pressure and temperature) are variables of optimization. The mathematical model is formulated using generalized disjunctive programming (GDP) and is optimized via mixed-integer nonlinear programming (MINLP), through the minimization of the retrofit total annualized cost, considering the turbine and compressor coupling with a helper motor. Three case studies are performed to assess the accuracy of the developed approach, including a real industrial example related to liquefied natural gas (LNG) production. The results show that the pressure recovery of streams is efficient for energy savings and, consequently, for decreasing the HEN retrofit total cost especially in sub-ambient processes.