【作者】 王芸；

【导师】 黄克谨；

【作者基本信息】 北京化工大学 ， 控制科学与工程， 2010， 硕士

【摘要】 为了降低石油化工分离过程中的能耗,热耦合技术得到了广泛的发展。与常规精馏塔相比,热耦合精馏技术在能耗及投资成本方面有着显著的优势。本文在热耦合精馏技术的基础上提出了一种新型的外部热耦合式复合精馏塔(简称EHIDDiC)。发掘外部热耦合式复合精馏塔在化工分离应用过程中的潜在优势是本文的主要目的。外部热耦合复合精馏塔由一个高压精馏塔和一个低压精馏塔构成,高压精馏塔的精馏段与低压精馏塔的提馏段进行外部热耦合。每一对耦合的塔板之间都有一个外部换热器。这样的外部热耦合方式避免了塔内换热面积的局限性以及换热结构的复杂性。本文以系统的年均投资成本TAC最优为设计目标,提出了一种外部热耦合复合精馏塔的系统性综合与设计的方法。考虑到EHIDDiC需要采用较多的外部换热器,不利于其在实际过程中的实现,因此本文在EHIDDiC结构的基础上,提出了一种外部热耦合复合精馏塔的简化构型,SEHIDDiC。该简化构型仅仅采用三个外部换热器来实现外部热耦合复合精馏塔中高压精馏塔精馏段与低压精馏塔提馏段之间的外部热耦合。一个外部换热器置于外部热耦合段的顶部,一个外部换热器置于外部热耦合段的中间,第三个外部换热器置于外部热耦合段的底部。通过对三个外部换热器的位置及换热面积的优化,来进一步提高SEHIDDiC的热力学效率。从而给出了外部热耦合式复合精馏塔的综合简化与设计方法。本文通过乙烯/乙烷和苯/甲苯两个二元物系的分离,应用文中提出的系统综合与设计的方法来研究外部热耦合复合精馏塔及其简化构型的性能。研究结果证实外部热耦合式复合精馏塔能够大大降低分离系统所需的能耗。与常规精馏塔相比,EHIDDiC的热力学效率更高,且所需投资成本更低。此外EHIDDiC经简化及优化以后,其所需的能耗及设备投资得到了进一步的降低,证实SEHIDDiC不但能够很好的近似EHIDDiC,而且为EHIDDiC这一个概念在实际分离过程中的设计及实施提供了一种更为简洁的方法。更多还原

【Abstract】 Heat-integration has been widely used to reduce the utility consumption in the separation operation in the chemical and petrochemical process industries. Compared with the conventional distillation column, the heat-integrated distillation process can lead to high thermodynamic efficiency and low total annual cost (TAC). A novel scheme of external heat-integrated double distillation columns, termed the EHIDDiC, is proposed in this thesis. The major purpose of this study is to explore the potential advantage of the EHIDDiC in the chemical and petrochemical process industries.The EHIDDiC have a high-pressure distillation column and a low-pressure distillation column. The rectifying section of the high-pressure distillation column is heat integrated with the stripping section of the low-pressure distillation column. There is an external heat exchanger between each pair of heat-integrated stages. The external type heat integration can avoid the problems of the internal heat integration and the complexity of heat transfer structure. With the minimum total annual cost as an objective function, a systematic method is proposed for the synthesis and design of the EHIDDiC.As the EHIDDiC needs a lot of external heat exchangers, it makes the EHIDDiC difficult to be designed and implemented in the practical situation. Thus, a simplified scheme of the EHIDDiC, termed as SEHIDDiC, should be derived, using only three external heat exchangers to approximate the external heat integration in the EHIDDiC. One external heat exchanger is placed between the tops of the heat-integrated sections; one is placed between the middles of the heat-integrated sections; the third one is placed between the bottoms of the heat-integrated sections. The locations and sizes of the three external heat exchangers are considered deliberately to maximize thermodynamic efficiency. A systematic method is derived for the SEHIDDiC.Two examples, i.e., the separations of an ethylene/ethane and benzene/toluene binary mixtures are employed to study the EHIDDiC and its simplified schemes. The results obtained indicate that the EHIDDiC is more thermodynamic efficient and needs less TAC in comparison with the conventional distillation column. Furthermore, the SEHIDDiC could be an excellent candidate to approximate the EHIDDiC with even a greater reduction in utility consumption and a less degree of capital investment. The SEHIDDiC offers essentially a much simple way to design and implement the concept of the EHIDDiC in the chemical and petrochemical process industries.更多还原