【作者】 罗立；

【导师】 姚平经；

【作者基本信息】 大连理工大学 ， 化学工程， 2004， 硕士

【摘要】 换热器网络主要用来回收过程工业中的能量，换热器网络综合方法的研究自六十年代至今方兴未艾。换热器网络的传热主要由双流股换热器来承担，该换热器应用非常广泛。多流股换热器作为一种特殊的、新型的换热器，主要应用在低温及深冷工业的传热中。但与双流股换热器相比，多流股换热器有其传热效率高、结构紧凑及投资低等优点。 多流股换热器网络的综合方法并不是很多，有的将整个换热网络综合成一台多流股换热器的，也有的以优化的双流股换热器网络为基础，再进行多流股换热器网络的综合。换热器网络综合方法研究目的是为了使换热器网络更好地应用于实际，为生产出谋划策。本文在优化的双流股换热器网络基础上，进行了多流股换热器的识别与构造；并充分考虑了实际应用的需要，建立了合适的换热器网络综合数学模型。 本文工作主要如下： 1)提出了多流股换热器在换热网络中的识别与构造规则 根据本研究所建立的双流股换热器网络超结构模型，应用遗传模拟退火算法，优化出双流股换热器网络，以此为基础，建立了多流股换热器网络的识别与构造规则。又将多流股换热器为一条流股与多条流股进行传热的“一对多”多流股换热器及多条流股与多条流股进行传热的“多对多”多流股换热器。按本规则综合出的多流股换热器网络年度化费用是最优的。 2)改进了原双流股换热器网络超结构模型 考虑工程实际，对原双流股换热器网络超结构模型进行了修改，限制了单个双流股换热器的热负荷并适当增加了级数。经过实例证明，在单个换热器热负荷被限制的情况下，原有的超结构级数不再符合优化的要求，因此建立了超结构级数的设定方法。单个换热器热负荷不受限制的情况下，优化的换热器网络会存在承担大换热量的大面积换热器，实际应用中它们会被几台定型的换热器代替，因此增加了换热器网络的设备费用。本文将单个换热器最大允许的热负荷作为一个约束条件在程序中进行优化，获得的双流股换热器网络与前者相比，在网络年度化费用上有一定优势；特别是在设备费用占网络总费用比率越大的情况下。 3)分析了多流股换热器网络综合过程中的“背包”问题 多流股换热器也有一定的规模，在多流股换热器网络的综合过程中，不一定都能将合适的双流股换热器都合并入同一台多流股换热器，这一点在合并规则中进行了描述。按改进的双流股换热器网络超结构模型综合出的双流股换热器网络，便面临着多种方案的选择，有点类似于数据结构中的“背包”问题。本文根据多流股换热器网络的识别与多流股换热器网络识别与构造的研究构造规则，详细描述了多流股换热器网络综合过程中的“背包”问题，再一次阐明了限制单个双流股换热器热负荷的必要性。 多流股换热器网络综合方法的研究对于工程应用是很有意义的，构造并设计出适用的多流股换热器，进一步扩大多流股换热器的使用范围，还有很多的工作要做。更多还原

【Abstract】 The heat exchanger network (HEN) is used to recover the energy of process system. Since 1960’s, the research to the synthesis of HEN is unceasing. The primary kind of heat exchanger is the single-hot and single-cold heat exchanger and this kind of heat exchanger is used in process industry such as petrochemical industry. The multi-stream heat exchanger is a new type of heat exchanger; it is currently used in gas processing. Compared with traditional single-hot and single-cold heat exchangers, multi-stream heat exchangers possess many advantages such as high heat transfer efficiency, compact structure and lower cost.Much work during the last half of century is focused on the conventional single-hot and single-cold heat exchanger networks; the research to the multi-stream heat exchanger networks is few. The way to the synthesis of multi-stream heat exchanger either synthesizes all streams to one multi-stream heat exchanger or merges some single-hot and single-cold heat exchangers to construct one multi-stream heat exchanger on the basis of optimized single-hot and single-cold heat exchanger network. The research aim for the multi-stream heat exchanger is to make them applied better in industry. This paper proposes a way of identification and construction for the multi-stream heat exchanger network on the basis of optimized single-hot and single-cold heat exchanger network, and forms the appropriate mathematical model considering the need of industry. The primary work is narrated as follows:1) Proposing the rule of identification and construction for multi-stream heat exchanger networksAt first, combining with the super-structure model, a genetic and simulated annealing algorithm (GA/SA) is used to get the optimized single-hot and single-cold heat exchanger network. Then the rules of identification and construction for multi-stream heat exchangers are proposed on the basis of this optimized network. The multi-stream heat exchanger is divided into two kinds, one is "one-multi" multi-stream heat exchanger in which the heat is exchanged between one stream and more streams, and the other is "multi-multi" multi-stream heat exchanger in which heat is exchanged between several streams and several streams. Of course, such annual network cost is the lowest according to the proposed rules in this paper.2) Modifying the original superstructure modelThe original superstructure model is modified by considering the model’s practicality. Inthe model, the heat load of single-hot and single-cold heat exchangers is limited and the number of stages is increased properly. Some examples prove the original way to determine the number of stages is inapplicable if the heat load of heat exchanger is limited, so a new way to determine the number of stages is established. There are many large-area single-hot and single-cold heat exchangers burdening a large of heat in original optimized HEN, they will be divided into many small heat exchanger in industry. It is no doubt that the cost of heat transfer equipment increases. This paper looks the allowable maximum heat load as one constraint in superstructure model, the optimized HEN by this way is better than the former in the annual network cost, especially when the equipment cost has a big ratio in total cost.3) Analyzing the bag problemThe selections for proper streams and heat load are faced because of the limit of multi-stream heat exchangers’ scale when the optimized single-hot and single-cold heat exchanger network according to the evolutional superstructure is synthesized to multi-stream heat exchanger network. This selection is the same to bag problem in data structure. This paper describes the synthesis process detailedly.The research to multi-stream heat exchanger network synthesis is significant for industry application. Much work should be done in designing the proper multi-stream heat exchanger and enlarging its scope in use.更多还原