【作者】 黄英博；

【导师】 黄克谨；

【作者基本信息】 北京化工大学 ， 控制科学与工程， 2011， 硕士

【摘要】 精馏过程是化学工业中的主要耗能单元,为了提高精馏过程中能量的利用效率,降低能量的消耗,热耦合技术得到了广泛的发展。热耦合技术主要包括内部热耦合和外部热耦合两种,其中内部热耦合技术由于其内部换热结构比较复杂,很难在工业生产中得到广泛的应用。外部热耦合技术是在精馏塔外进行热量的耦合,因此,大大降低了热耦合的复杂性。外部热耦合技术最早是根据变压精馏过程提出的,Luyben等人首先研究了高压精馏塔冷凝器与低压精馏塔再沸器耦合的情况。考虑到耦合程度与能耗的关系,Huang等人研究了高压塔精馏段与低压塔提馏段耦合的情况,并将该结构命名为外部热耦合式复合精馏塔(简称EHIDDiC)。Huang等人通过大量的仿真计算已经证明了外部热耦合式复合精馏塔可以有效地利用余热,提高系统的热力学效率,达到很高的节能幅度,但仍缺乏实验数据的支持。因此本文旨在从实验的角度来验证外部热耦合原理的节能效果。外部热耦合式复合精馏塔是将高压精馏塔精馏段(包括塔顶冷凝器)放出的热量传递到低压精馏塔提馏段(包括塔釜再沸器),从而实现热量的耦合,对应的耦合塔板之间设有外部换热器,当耦合塔板数较多时,相应的需要使用较多的外部换热器,这就导致外部热耦合式复合精馏塔实验设备的建造难度增加,因此在外部热耦合式复合精馏塔的基础上,以系统的年度总费用TAC最小为设计目标,对外部热耦合式复合精馏塔进行优化,得到简化的外部热耦合式复合精馏塔(简称SEHIDDiC),该简化结构仅采用3个外部换热器来进行热量的耦合,使设备建造的难度大幅度降低。根据简化的外部热耦合式复合精馏塔,我们对外部热耦合式复合精馏塔的实验设备进行了设计。设计部分主要包括外部热耦合式复合精馏塔实验装置的材质选择,精馏塔的塔径,系统的处理量等设计参数的计算,以及该实验装置中的检测和控制设施的设计。外部热耦合式复合精馏塔实验部分主要介绍了实验内容,实验结果以及对实验结果的分析。其中实验内容主要包括系统开车试验,以及系统稳态实验；稳态实验中包括蒸汽上升至塔顶、全回流、正常进出料三种状态的实验,每种状态的实验包括应用外部热耦合与不应用外部热耦合两种情况；应用外部热耦合的实验包括开启不同个数换热器和不同换热器组合的实验。由于实验室条件和实验设备的限制,使得部分实验无法顺利进行。为了能够进一步分析外部热耦合式复合精馏塔在实际分离过程中的特点,需要对实验设备进行模型化,通过模型对无法在实验设备上实现的情况进行研究讨论。本次研究选择正丙醇和异丙醇二元物系作为分离对象,根据对实验结果以及模拟结果的分析,初步验证了外部热耦合式复合精馏塔在实验过程中的节能效果,为外部热耦合式复合精馏塔应用于实际生产过程奠定了基础。更多还原

【Abstract】 Distillation process is the main energy-consuming chemical industry unit. In order to improve the thermodynamic efficiency of the distillation, and reduce energy consumption, thermal coupling technology has been widely developed. Thermal coupling technology includes internally heat-integrated technology and externally heat-integrated technology. Due to the complex internal structure, the internally heat-integrated technology is difficult to be achieved in industrial production. The heat-integration of the externally heat-integrated technology is outside of the distillation column, therefor, the complexity of the heat-integration will be greatly reduced. Theoretical studies have shown that the externally heat-integrated technology can effectively use waste heat to improve the thermodynamic efficiency of the distillation system and cut the energy consumption with a large range. But there are no experimental data to support it. This article aims to verify the energy saving effect of the externally heat-integrated technology from the experimental point of view.The externally heat-integrated double distillation columns (EHIDDiC) include a high-pressure distillation column and a low-pressure distillation column. The rectifying section of the high-pressure distillation column (include the condenser) transfer heat to the stripping section of the low-pressure distillation column (include the reboiler). There is an external heat exchanger between each pair of heat-integrated stages. Compared with the internally heat-inteagrated distillation column, the EHIDDiC can avoid the limitation from the heat transfer area and simplify the structure of heat exchange.Due to the vast external heat exchangers, the externally heat-integrated structure is difficult to achieve in the actual process. So, on the basis of EHIDDiC, with the minimum total annual cost as an design goal, a simplified scheme (SEHIDDiC) has been derived, which only uses three external heat exchangers to approximate the external heat-integration.According to the SEHIDDiC, we carried out the design of expetimental equipment. This section includes choosing material of the external heat-integrated double distillation columns, calculating the column diameter, the handling capacity and other design patameters. In this section, the measurement and control facilities of the experimental apparatus are also designed.The experimental part of this paper introduces the content and results of the externally heat-integrated double distillation columns experiment. The content mainly includes the system start-up and the steady-state experiments. The steady-state expetiments include the vapour rising to the top, total reflux, the normal state with feed and products. Externally heat-integrated experiments include adjusting the number and combination of the heat exchangers.As the limitations of laboratory equipment, many experiments can not be achieved. In order to further analyze the performance of actual distillation using external heat-integration, a model of the experiment device should be established. Through the model, we can study and discuss the situations which can not be achieved in the laboratory equipment.The binary mixture of n- and i- propanol is selected as a separation object. Based on the analysis of the experimental results, the energy-saving effect of the externally heat-integrated double distillation columns in the acture saparation process has been preliminary verified. This study lays a foundation for the use of externally heat-integrated double distillation columns in the actual chemical production.更多还原