【作者】 陈挹；

【导师】 盛颂恩； 蒋宁；

【作者基本信息】 浙江工业大学 ， 流体机械及工程， 2010， 硕士

【摘要】 随着世界性能源危机的加深,过程工业的系统节能越来越受到人们的重视。换热网络作为过程工业中能量回收的重要系统,其设计水平的高低直接决定了过程系统的能耗和经济性。因此,换热网络的最优综合逐渐成为人们研究的热点问题。与此同时,现有的各类换热网络的综合方法都存在着一些问题和缺陷,迫切需要深入研究。在现有的各类换热网络的综合方法中,夹点设计法较为成熟,这种方法的理论基础建立在过程系统中的流股具有相近的传热膜系数基础上,但是在实际的过程工业中这种假设并不成立,因此本文在引入温差ΔT-贡献值的基础上,针对传热膜系数有较大差异的过程系统,进行换热网络综合的研究。本文围绕这一主题,主要开展的研究工作如下:1.本文首先从传热温差驱动力的角度出发,对确定流股ΔT-贡献值的关联式进行了论证和推导,因为流股的ΔT-贡献值是本文方法的基础。在此基础上提出了基于ΔT-贡献值的系统性换热网络综合方法,给出运用此方法进行网络综合的流程步骤,并通过一个案例对此方法进行研究和讨论,结果表明:运用此方法综合换热网络时,能够合理地对传热温差进行分配,从而减小了换热面积和年度总费用。2.本文通过对基于ΔT-贡献值的换热网络综合方法的深入研究,进一步提出了基于ΔT-贡献值法的三级优化策略,并给出了基于三级优化策略综合换热网络的具体实施步骤。本文分别对这三步优化进行了详细的阐述,着重研究讨论了参数κ、z的寻优范围,并在此范围内通过二维优化方法进行寻优;而参数κ、z的优化过程中又包含了网络超结构的优化,其关系为内嵌关系,即在求解网络超结构的热负荷分配时,需进一步对网络超结构进行优化,从而在能量费用一定的情况下,使得投资费用降低;最后一步优化则是通过网络调优和能量松弛,进一步简化换热网络的结构,提高网络的适应性和调节性。3.本文在上述理论基础上,基于MATLAB GUI软件设计平台开发了换热网络综合的软件。该软件能够采用常规夹点设计法和本文提出的基于三级优化策略的ΔT-贡献值法来合成换热网络,为本文的理论研究提供了快速验证和比较平台,随后的案例研究也对本软件系统的有效性和实用性进行了检验。4.最后,本文运用开发的换热网络综合的软件对几个案例进行了分析和研究,第一个案例着重对基于三级优化策略综合换热网络的详细步骤进行阐述,后两个案例着重对工程实际的过程系统进行网络综合。网络综合的结果表明,与传统夹点设计法相比,运用本文提出的综合方法能够合理地对传热温差进行分配,降低了网络换热面积,年度总费用较小,网络结构简单,可用于解决流股传热膜系数不同的实际换热网络集成问题。更多还原

【Abstract】 With the deepening of the world energy crisis, the energy saving of process system is by more and more people’s attention. As an important energy recovery system of process industrial, heat exchanger networks design directly determines the level of energy recovery and economy of the process system. Therefore, heat exchanger networks synthesis gradually becomes a hotspot. Meanwhile, the existed methods of heat exchanger networks synthesis exist some problems and defects, need further research urgently.In the existing methods of heat exchanger networks synthesis, pinch design method is a mature one, and its theoretical basis is based on the similar heat transfer coefficient of the streams in the process system, but this assumption is not practical in the actual process industry. Therefore, this paper aimed at the process system with different heat transfer coefficient of streams, researched heat exchanger networks synthesis based on the theory ofΔT-contribution. Based on this topic, the main research work are as follows:1. This paper deducted the relational theory formula ofΔT-contribution values in the view of the heat transfer driving force, becauseΔT-contribution of streams is the foundation of the method proposed in this paper. On the basis ofΔT-contribution, this paper proposed the method of heat exchanger networks synthesis systemically. This paper displayed the detailed steps of this method, discussed and studied this method through a case study, the results show that: this method is reasonable to the transfer temperature’s distribution, thus can reduce the area and the total annual cost of heat exchanger networks.2. Through the deep research of heat exchanger networks synthesis method based onΔT-contribution values, this paper put forward the three-level optimization strategy and introduced the detailed procedure. This paper studied the three-level optimization strategy in deep, studied and discussed the range of parametersκand z, and used a two-dimensional optimization method in this range. This process includes the optimization of superstructure, that is we need further optimize the superstructure of networks, thus in the fixed energy cost, we can get lower investment cost. The last step is networks optimization and energy relaxation, further simplify the structure of heat exchanger networks, improve the flexibility and regulatory.3. On the basis of theories upwards, this paper developed the software of heat exchanger networks synthesis based on MATLAB GUI. This software can use the conventional pinch design method to synthesize heat exchanger networks. At the same time, the method proposed in this paper can also be used in the software to synthesize heat exchanger networks. The software provides a quick test and comparing platform for this paper’s theory research. Subsequently, the effectiveness and practicability of the software system is tested by some case studies.4. Finally, several cases were analyzed and studied using the software of heat exchanger networks synthesis. The first one focused on the detailed steps of the three-level optimization strategy, and another two cases lay stress on networks design to the actual process system. The results show that compared with the traditional pinch design method, the transfer temperature’s distribution is more reasonable using the method this paper proposed, the area and the total annual cost are lower, the structure of networks can be simpler. The method this paper proposed can be used to solve actual heat exchanger networks synthesis problems with the streams having different heat transfer coefficient.更多还原